Model 16HD, 32HD & 64HD - Miniature Pressure Scanners Manual

Chell Instruments Ltd Folgate House Folgate Road North Walsham Norfolk NR28 0AJ ENGLAND Tel: 01692 500555 Fax: 01692 500088 microDAQ Pressure Scanner Acquisition System INSTALLATION AND OPERATING MANUAL e-mail:- info@chell.co.uk Visit the Chell website at: http://www.chell.co.uk 900165-1.1 Page 1 Please read this manual carefully before using the instrument. Use of this equipment in a manner not specified in this manual may impair the user’s protection. Chell Document No. : 900165 Issue 1.1 ECO : 669 Date: 20th March 2012 Chell’s policy of continuously updating and improving products means that this manual may contain minor differences in specification, components and circuit design from the actual instrument supplied. Page 2 CONTENTS CONTENTS ................................................................................................................................ 2 1 Description ............................................................................................................................ 3 1.1 General ...................................................................................................................................................... 3 2 Specification ....................................................................................................................... 4 2.1 Power Supply: ........................................................................................................................................... 4 2.3 CAN specifications: ................................................................................................................................... 4 2.4 Serial specifications: .................................................................................................................................. 4 2.5 Ethernet Specifications: ............................................................................................................................. 4 2.6 Operating conditions: ................................................................................................................................ 4 2.8 Measurement specifications: ..................................................................................................................... 4 3 Installation and Interconnections ...................................................................................... 5 3.1 Connector – Mating connector: DEUTSCH AS606-05SN-HE ................................................................... 5 3.2 USB Connector – Mating connector: Micro B ........................................................................................... 5 3.3 Scanner Connector – Internal micro miniature ‘D’ type, female. ............................................................... 5 4 Operation of the instrument ............................................................................................... 6 4.1 Connecting up the microDAQ. .................................................................................................................. 6 4.2 Installing the software. ............................................................................................................................... 6 4.3 Re-zeroing the microDAQ. ......................................................................................................................... 6 4.4 Hardware Trigger ........................................................................................................................................ 6 4.5.1 Hardware Trigger Input. ....................................................................................................................... 6 4.5.2 Timing Information ............................................................................................................................... 6 4.5.3 Software Control .................................................................................................................................. 7 5 ‘microDAQ Setup’ Configuration Software ........................................................................... 8 5.1 Introduction. ................................................................................................................................................ 8 5.2. The 'Setup Parameters' Tab. ..................................................................................................................... 8 5.2.1 Introduction. ......................................................................................................................................... 8 5.2.2 Signal Parameters. .............................................................................................................................. 8 5.2.3 CAN Parameters. .............................................................................................................................. 10 5.2.4 TCP/UDP Parameters. ...................................................................................................................... 11 5.2.5 RS232 Parameters. ........................................................................................................................... 12 5.2.6 Remaining Sundry Parameters. ........................................................................................................ 13 5.2.7 The COM Frame................................................................................................................................ 15 5.3. 'Live Data'. ............................................................................................................................................... 15 5.4. 'Calibration'. ............................................................................................................................................ 16 5.5. 'DTC Information. .................................................................................................................................... 19 6. Service and Calibration ...................................................................................................... 21 6.1 Service ..................................................................................................................................................... 21 6.2 Calibration................................................................................................................................................ 21 6.3 Adjustment ............................................................................................................................................... 21 6.4 Cleaning ................................................................................................................................................... 21 Page 3 1 Description 1.1 General The microDAQ is a self contained acquisition system and combined pressure scanner that acquires and transmits data to a host via USB, Ethernet or a CAN bus. It is the next generation of the popular Chell CANdaq acquisition system. The microDAQ comes in several variants to accommodate both conventional HD series scanners and Digital Thermal Compensation (DTC) scanners with 16, 32 and 64 channels. The microDAQ is supplied with all the software required to configure it and read the data from it. The microDAQ addresses the scanner at a defined rate, acquires the output and applies a pressure and thermal calibration to derive the engineering units. The microDAQ can be re-zeroed at any time either from a host controller via comms or by closing contacts between two pins on the Autosport connector (if configured in this mode). The microDAQ also has a hardware trigger like the Mk3 CANdaq system, to give some time determination to the data acquired. This manual covers firmware version 1.0.2. Page 4 2 Specification 2.1 Power Supply: Line voltage: 9-36 VDC. Consumption(CANdaq only): With a 64 channel scanner: Max 15VA 2.3 CAN specifications: CAN type 2.0B CAN baudrate Configurable (by internal switch) from 1M, 500K, 125K and 100K. Programmable variables: Address 0x?nn Most significant programmable device ID Address 0xn?n Next most significant programmable device ID BRP CAN bus timing – see Infineon data sheet TSEG1 CAN bus timing – see Infineon data sheet TSEG2 CAN bus timing – see Infineon data sheet SJW CAN bus timing – see Infineon data sheet 2.4 Serial specifications: USB2.0 (micro) 57600 baud, no parity, 8 data bits and 1 stop bit. 2.5 Ethernet Specifications: TCP/IP 10Mb/s & 100Mb/s via Auto Negotiation TCP & UDP protocols supported 2.6 Operating conditions: Operating temperature range: +5°C to +50°C (40°F to 122°F) Storage temperature range: -20°C to +70°C (-40°F to 158°F) Maximum Relative humidity: 95% at 50°C (non condensing) 2.8 Measurement specifications: System accuracy: ±0.25% FS for conventional scanners ±0.06% FS for DTC scanners ±0.06% FS for I-Daq scanners Resolution: 16 Bit Maximum Measurement Speed: See table below: Number of Scanner channels Acquired 16 32 48 64 Speed M/C/S 1250 625 400 300 All measurements are in measurements / channel / second.Page 5 3 Installation and Interconnections 3.1 Connector – Mating connector: DEUTSCH AS606-05SN-HE Pin Number Designation 1 TX+ 2 RX+ 3 TRIGGER IN (TTL) 4 +8~25V SUPPLY 5 0V 6 CAN_H 7 CAN_L 8 TX- 9 RX- 3.2 USB Connector – Mating connector: Micro B Pin Number Designation 1 +5v USB transceiver supply 2 USBDM 3 USBDP 4 N/C 5 0V 3.3 Scanner Connector – Internal micro miniature ‘D’ type, female. Pin number Signal 1 Address line A0 2 Address line A1 3 Address line A2 4 Address line A3 5 Address line A4 6 +12VDC 7 -12VDC 8 +5VDC (Vs) 9 +5VDC RTN 10 Ground 11 Output 12 Address line A5 13 Ov sense 14 Not used 15 Temperature signal Page 6 4 Operation of the instrument 4.1 Connecting up the microDAQ. The microDAQ has one connector and cable which supplies the unit with power and also provides CAN and Ethernet comms. An industry standard micro USB (typeB) connector is provided to allow for RS232 connection for changing the setup parameters of the. Ensure all the connections are made before powering up the microDAQ. Upon power up, the blue LED will light constantly while the microDAQ boots up. This boot-up period will vary depending on the type of scanner and the number of channels. The boot up time is also influenced by the Ethernet initialisation process. This process requires a valid network connection to perform auto negotiation and link check status. If there isn’t a valid connection the process waits until either a network is found or the timeout occurs. This timeout is configurable via setup and ranges from 0 to 30 secs per check (2 checks). When the microDAQ has finished booting, the blue LED will flash at a constant rate to show that the system is running. 4.2 Installing the software. The microDAQ interface software should now be installed so that the microDAQ may be configured. Simply run the appropriate setup.exe on the CD provided. 4.3 Re-zeroing the microDAQ. Before any measurements are made, the microDAQ should be re-zeroed. The microDAQ may need further re-zeroing if the unit or scanner should be subject to significant thermal variations. The microDAQ is re-zeroed by sending the appropriate command over the CAN, USB or Ethernet link via the Chell software. The system will then average a number of zero readings and perform a re-zero. Naturally, there should be no pressure applied to the ports of the scanner when a re-zero is being performed. When a re-zero is being performed, the red LED will light momentarily. 4.4 Hardware Trigger The microDAQ features a hardware trigger to enable the user to synchronise multiple microDAQ’s and to calculate the timing of the measurements made. The hardware trigger takes the form of a pulse train. Each time the microDAQ receives a positive edge, it will generate a set of measurements for all the channels configured in the system. 4.5.1 Hardware Trigger Input. The hardware trigger input is a 5V TTL square wave pulse train. Minimum frequency 2Hz and maximum frequency 1KHz (16 channels only). 4.5.2 Timing Information The hardware trigger allows the user to calculate the time of each measurement. For example if the hardware trigger were running at 100Hz then the user would receive 100 measurements per channel per second. The first pulse would generate the first set of measurements and 10ms later the second pulse would generate the second set and so on. When the hardware trigger is activated, the microDAQ will wait for the first pulse. The time that this first pulse is generated can be measured by the user and therefore the time of the first set of data and all subsequent sets can be determined. For more details on hardware trigger timing a technical paper is available – Chell Page 7 document no. 900118 (this paper was developed for the CANdaq but applies to the microDAQ as well). 4.5.3 Software Control The hardware trigger mode is activated by the T command over the RS232, CAN or Ethernet interfaces. The T command can be used to enable the hardware trigger that will cause the microDAQ to stop free-running and wait for the first pulse. The disable command will return the microDAQ to free-running. The command structure is as follows: Command Interface On / Off T00 RS232 Off T10 RS232 On T01 CAN Off T11 CAN On T02 Ethernet Off T12 Ethernet On Page 8 5 ‘microDAQ Setup’ Configuration Software 5.1 Introduction. microDAQSetup provides the means of setting up, calibrating and demonstrating the microDAQ unit from a standard PC with a serial port. Version 1.0.3 is written to complement microDAQ firmware V1.0.2. The software is divided by tabs into five areas of functionality, namely 'Setup Parameters', 'Live data', 'Calibration', 'DTC Information'. and ‘Tools’ 'Setup Parameters' provides the means to set microDAQ’s operating parameters and its identification information. The unit's function may be checked and demonstrated using 'Live Data' to show attached pressure scanner raw readings and microDAQ’s calibrated output. 'Calibration' gives access to microDAQ's existing on board, non DTC calibration coefficients, the tools for performing a new calibration, namely calculating and downloading new coefficients, and the means to managing calibration data. Data from the calibration procedure and resulting coefficients may be loaded, stored and exported for filing, reuse and examination in other packages. 'DTC Information' provides a means for interrogating a DTC variant of the microDAQ, the user having access to identification information, the current status of the calibration shuttle valve and both excitation and temperature voltages. ‘Tools’ provides some functionality to read DTC coefficients and current scanner values and change the MAC address of the Ethernet hardware. This tab is not readily available to everyone. 5.2. The 'Setup Parameters' Tab. 5.2.1 Introduction. The 'Setup Parameters' tab allows the reading and writing of all of microDAQ's operating settings to its on board non volatile EEPROM. The operator may upload the current settings from microDAQ, edit them, and then download them back into the unit. A submenu of tabs divides the available setup parameters into different categories by function, and each category is detailed separately in the following. Figure 5.1 shows the common controls and the 'Signal' group of parameters. The function of the common controls is detailed in the subsequent table. 5.2.2 Signal Parameters. The microDAQ has settings to allow the user flexible control over the data throughput of the device. Averaging options allow the preference of noise reduction over time domain response, the frequency of calibration temperature compensation renewal may be chosen as may be the size of the average (and hence time taken) for the rezero routine. Table 5.1 details the function of the signal parameter option controls. Page 9 Control Function 'Pressure Input Impulse Filter' Check box to apply impulse filter to pre calibration data - will remove single impulse noise events in the pressure data. 'Temperature Input Impulse Filter' As above but with temperature data. 'Pressure input average samples' Selects the number of samples for a rolling average of pre calibration pressure data. 'Temperature input average samples' As above but with temperature data. 'Pressure output average samples' Selects the number of samples for a rolling average of post calibration pressure data. 'Reset average on output' Overrides the rolling pressure output filter. When checked, the unit builds a fresh post calibration average between each data delivery event. 'Temperature Compensation' Selects the temperature compensation scheme for the calibration. 'Continuous' repeatedly rebuilds the calibration data on a channel by channel basis without interrupting the flow of data. 'Demand only' permits the use of a designated user command to request a rezero. 'Periodic', and the selected 'Compensation Period' force a compensation operation at designated intervals. 'Rezero average samples' The number of samples in the average to calculate a new pressure zero offset. ‘Rezero Tracking Band’ Set the region (+ or – %FS from zero) where the unit tracks the output to zero after a rezero operation. Select ‘Off’ to disable the function. Table 5.1, Function of the 'Signal' parameter controls Figure 5.1, Contents of the 'Setup Parameters' tab, Signal Tab and Engineering Functions Selected. Page 10 Control Function Common Functions 'Connect and Read' button Retrieves all setup data from microDAQ including software version, setup parameter values and identification. Diagnostic information may be seen in the central listbox. 'Burn Settings' button Downloads setup values and identification strings to microDAQ, then writes them into the EEPROM. Diagnostic information may be seen in the central listbox. 'Rezero' button Starts a microDAQ rezero operation. 'RESET' button Resets the microDAQ, similar to power cycling the device. Use to activate new settings and/or rebuild calibration tables. 'Channels' dropdown The number of channels on the attached scanner should be chosen from the 'Channels' drop down. It is important that this number is correct when performing any calibration or reading data from microDAQ. 'Full Scale' dropdown This dropdown is the only means of selection of the scanner's full scale operating pressure. The value affects the display of live engineering values and the generation of calibration coefficients. ‘Wizard’ button Start the setup wizard for a simple way to apply common settings to the microDAQ. ‘Rebuild’ button Force a calibration table rebuild. ‘Start Capt.’ button Start capturing characters received on the serial port to the text file *********, and display on the engineering screen. ‘Stop Capt.’ button Stop capture of serial characters. ‘Engineering Functions’ checkbox Show or hide the engineering functions panel. For calibration file management controls, see the calibration section. Table 5.2, Common setup control functions. 5.2.3 CAN Parameters. The optional CAN communication parameter controls are shown in figure 5.2. Options control the CAN bus baudrate, the rate of data delivery, the number of channels enabled and the data format. Additionally the base message number may be selected, as can the offset from this base number for the reception of user commands over CAN, and whether an acknowledgement of these user commands is sent on the next higher message number. Data may be transmitted on either multiple messages, or alternatively on a single message ID, with a selectable delay between messages. Figure 5.2, CAN parameters within the setup data. Page 11 'CAN baudrate' Shows the setting of the four register values required to set up the CAN bus timing in CANdaq's microcontroller. Selecting a CAN baudrate from the combo box sets different register values to achieve one of a number of preset baudrates. The user is free to set their own preference in consultation with the appropriate datasheet. Note the internal CAN peripheral clock runs at 60Mhz. All register values should be calculated based on that clock frequency. 'CAN First TX Message ID’ microDAQ uses standard CAN message arbitration id's, and the unit is assigned the most significant 2 digits of the Hex base address. For the digits 0x1A for example, data for the first 4 channels will be sent on 0x1A0, the next 4 on 0x1A1 etc Message scheme/delay Select ‘Multiple Messages’ for the 4 channels per message, multiple message scheme. Alternatively data may be packed 3 channels per message + identifier byte, with a selectable delay between messages. 'Active CAN channels' Allows the selection of a subset of total scanner channels to be active. 'CAN data rate' The delivery rate of data for each channel 'CAN protocol' The data format delivered by the CAN module. Can be 16 bit data, as two bytes (either big or little ended) . ‘CAN RX ID Offset’ Selects the hex offset from the base message ID where microDAQ will receive incoming user commands (see user command document). If ‘Ack. Enabled’ is selected, the unit will acknowledge the reception of a correctly formatted command on the message ID calculated as Base ID + RX Offset + 1 BRP, TSEG1, TSEG2, SJW Register values for the CAN module within microDAQs microcontroller. Table 5.3, CAN parameter control functions. 5.2.4 TCP/UDP Parameters. The optional TCP/UDP communication parameters Standard controls are shown in figure 5.3a. Options control microDAQs IP address and subnet mask, in addition to any gateway IP address required. Options for channels and delivery rate and protocol are the same as for the CAN system above. microDAQ's active TCP listening port is fixed at 101. The Advanced tab (figure 5.3b) allows changing of the primary & secondary DNS addresses (not currently used by the microDAQ), and also a setting for the Ethernet initialisation timeouts. The UDP tab (figure 5.3c) holds all the settings specific to UDP. In UDP mode each acquisition cycle (of ‘x’ number of channels) is packed as a separate UDP packet with a four byte representation of the microDAQ serial number at the start of the packet. These are attempted to be sent out at the required rate but with no checking for reception or validity of data. The microDAQ’s UDP port is also fixed at 101. Settings available from this tab include setting the UDP address and port for a remote connection (for auto streaming via UDP at boot up) and a setting for auto broadcasting a UDP message at bootup to inform the network of the availability of the microDAQ. Note that selecting Engineering Units for a protocol will cause the scanner addressing rate to be reduced; it is better to scale calibrated 16 bit data to engineering units within the client software. Figure 5.3a, TCP/UDP parameters (Standard tab) within the setup data. Page 12 Figure 5.3b, TCP/UDP parameters (Advanced tab) within the setup data. Figure 5.3c, TCP/UDP parameters (UDP tab) within the setup data. 'IP Address' IP address allocated to microDAQ on the user's network. 'Subnet' Subnet mask as set on the user's network. 'Gateway' IP address of the gateway on the user's network. 'Active TCP channels' Allows the selection of a subset of total scanner channels to be active. 'TCP rate' The delivery rate of data for each channel 'TCP protocol' The data format delivered by the TCP module. Can be 16 bit data, as two bytes (either big or little ended) or engineering units. ‘Enable User Command Acknowledgement’ If checked, returns acknowledgement to incoming user TCP commands. Primary & Secondary DNS Addresses of Primary and Secondary DNS servers (not currently used on microDAQ) Ethernet Initialisation Check Timeouts At bootup the Ethernet module performs two checks for auto negotiation and link check status. This timeout can be controlled via this text box. If Ethernet comms are not going to be used then this value can be set at 0 to speed up startup time. Use UDP If checked, uses the UDP protocol rather than the TCP protocol for Ethernet transmission. Each packet is one cycle of data acquisition with 4 byte representation of microDAQ serial number at the start. Remote UDP IP address and port Address and port of remote connection to mic roDAQ. If set then the microDAQ can be set to auto stream data to that remote host on boot up (after initialisation) Auto Broadcast UDP message on boot If checked, auto broadcasts a UDP message on port 10001 on startup which details the microDAQs serial number, IP address, etc. in an ASCII, comma separated list. (should not be used if remote UDP address/port has been configured and auto streaming has been set – via TCP rate on Standard tab) Table 5.4, TCP parameter control functions. 5.2.5 RS232 Parameters. The data delivery options of CAN and TCP are repeated for the RS232 interface, in addition to a baudrate selection allowing user configuration of microDAQ’s baudrate on powerup. The baudrate selected is valid for both data delivery functions, and communication to the setup software. Note that selecting Engineering Units for a protocol will cause the scanner addressing rate to be reduced; it is better to scale calibrated 16 bit data to engineering units within the client software. Page 13 Figure 5.4, RS232 parameters within the setup data. 'RS232 baudrate' microDAQ communication baudrate for both data streaming and user interface 'Active RS232 channels' Allows the selection of a subset of total scanner channels to be active. 'RS232 data rate' The delivery rate of data for each channel 'RS232 protocol' The data format delivered by the RS232 module. Can be 16 or 14 bit data, as two bytes (either big or little ended) or engineering units. ‘Enable User Command Acknowledgement’ If checked, returns acknowledgement to incoming user RS232 commands. Table 5.5, RS232 parameter control functions. 5.2.6 Remaining Sundry Parameters. The remaining parameters are edited via the 'ETC' tab, shown in figure 5.5. Scanner and microDAQ identification strings may be written 'as is' to the device, as may a date. If the microDAQ is a DTC variant and DTC mode is to be used, the 'Use DTC' checkbox should be checked. If the microDAQ is an I-daq variant then the ‘use raw calibration’ checkbox can be ticked to apply a linear calibration function on boot up. The DTC scanner's options of sensistor and gain configuration may also be selected from this tab. 'All DTC Channels Active', defaults the number of active channels to all on a DTC scanner, overriding the number in the setup. The ‘Trig In’ line on the Autosport connector can be configured to be used for Hardware Trigger or Mute/Rezero. The scanner type should always be set to the type of scanner installed in the microDAQ to ensure proper operation of the system. Figure 5.5, Remaining ('ETC') parameters within the setup data. 'Scanner ID' Provision for a scanner serial number. 'CANdaq ID' Provision for the microDAQ serial number 'Date' Provision for a date field - the software defaults to the system build date. 'Use DTC calibration if available' On powerup, uses the DTC scanners internal calibration coefficients to build the microDAQ’s internal calibration data table. Page 14 If I-daq detected, use raw calibration If checked, this replaces the normal polynomial calibration function with a ‘raw’ linear function whenever an I-daq is present in the microDAQ. 'Sensistor in circuit' If checked, keeps the sensistor in circuit for a DTC scanner. In normal operation this control should be left unchecked. 'DTC gain = 1/3' Selects the deranging function of the DTC scanner if the '3' option is selected, otherwise defaults to the standard range of the scanner. 'All DTC Channels Active' If checked, defaults microDAQ to setting the number of active channels to the number read from the DTC scanner header 'Span Calibration to DTC Full Scale' If checks, defaults the span of the calibrated output to the full scale read from the DTC scanner header. 'Span High' Sets the value of pressure for the 'high' point in the linear span and zero calibration. Valid values range from 0.144PSI (3”WC) to 90PSI. Scanner Type Sets the type of scanner installed into the microDAQ (Conv, DTC, I-Daq, T-DAQ) [Trig In] line options Selects the use of the [Trig In] hardware line on the Autosport connector. Table 5.6, Remaining ('ETC') parameters within the setup data. Page 15 5.2.7 The COM Frame. The 'COM' button towards the bottom right of the main from, toggles the frame it sits in between the 'RESET' frame as seen in figure 5.1 and the 'PING' frame, as seen in figure 5.6 below. Access to the communications port settings and the ping function of determining the current software version of the microDAQ is from this alternate frame. The red indicator shows the software is connected to the serial port. Figure 5.6, The alternate 'PING' frame accessed from the 'COM' button. 'Ping CANdaq' button To confirm that the attached microDAQ is alive and communicating, clicking the ping button retrieves the current software version string from the device and displays it in the label next to the button. COM port parameters The software defaults to the last used microDAQ serial port operating settings, though these settings may be overwritten by typing the desired settings into the text box and clicking the '>>>' button. NOTE: ensure the USB cable is connected to the microDAQ before clicking the ‘>>>’ button to connect and ALWAYS click the ‘<<<’’ button to disconnect before disconnecting the USB cable from the microDAQ. Table 5.7, Functions within the alternate 'PING' frame accessed from the 'COM' button. 5.3. 'Live Data'. Figure 5.7 shows the 'Live Data' tab of the software selected for a 64 channel pressure scanner. Figure 5.7, Contents of the Live Data Tab Page 16 The live data tab is a means to demonstrating the correct operation of microDAQ and testing the unit's calibration. By selecting the correct number of channels for the attached scanner, the software shows a data label dedicated to each. The type of value shown in the label may be selected by means of the option buttons to the right of the frame, the user selecting between raw (decimal 16 bit unsigned), calibrated (decimal 16 bit unsigned) and engineering units or voltage scaled to the known full scales. Also for DTC scanners, the temperature values as raw unsigned 16 bit and calibrated engineering units may be displayed. Once a type is selected, clicking the start button causes continuous reads of microDAQ until the stop button is pressed. Clicking the start button will cause most of the function buttons within the software to be disabled, preventing their operation until the 'Stop' button is pressed. The 'Derange' checkbox allows the application of a constant to the data in the case of the DTC deranging function being active - the value of this constant may either be typed into the text box, or reading the DTC header will automatically fill in this value The live data may be logged to a comma delimited file by checking the 'Log to Disk File' checkbox. Checking the file causes a new file to be opened in the current data directory, with a filename of the form 'microDAQlive_DDMMYY_n.csv' (where DDMMY is the current date and n is a number incremented with each checking of the checkbox). Each time a set of live values is read from microDAQ they are written in the current selected format to the disk file. Unchecking the checkbox causes the current file to be closed. The name of the last file generated is shown in the white text box on the form. For non DTC scanners, the temperature value read from the scanner is displayed in the Temperature Reading label. 5.4. 'Calibration'. The 'Calibration' tab allows access to microDAQ’s existing non DTC calibration coefficients and provides a means to acquiring live calibration data and calculating new coefficients. The loading, saving and export of both tests and coefficients is also possible from this tab. Calibrations may either be 3 temperature based for a temperature calibration, or by unchecking the 'Temperature Cal.' checkbox, a non temperature calibration may be performed at a single temperature. Figure 5.8 shows the 'Calibration' tab controls which are further explained in table 5.8. The software maintains two sets of coefficients - those uploaded from microDAQ and a local set, which is either loaded from the file of a previous calibration, or calculated from live or reloaded test data. Either of the two sets may be examined by choosing which is viewed via the 'Remote' or 'Local' tab, and selecting the channel from the dropdown box. The compare button may be used to compare the local set with the microDAQ upload set to confirm a successful burning of new coefficients. Other controls include the 'Send and Burn' button which writes the current local coefficients to microDAQ EEPROM. The 'Clear' button sets all local coefficients to zero. The ‘Actions’ buttons may be seen in figure 5.9. Page 17 Figure 5.8, Contents of the Calibration Tab. Control Function Temperature tabs Select at which temperature the unit is currently been calibrated Applied Pressure The engineering units pressure setpoints - user entered, or set to standard values (+/- FS, +/-0.5FS, 0) by clicking 'Defaults' Pressure 16 bit The 16 bit unsigned representation of the pressure setpoints, calculated by the software Read value 14 bit The raw value read by microDAQ from the pressure scanner for the pressure setpoint Temperature 14 bit The temperature value read by microDAQ from the pressure scanner at that pressure setpoint Accept button Clicking 'Accept' stores the current read value as the calibration point, and moves on to the following setpoint Defaults Sets the default calibration points as +/- full scale, +/- 0.5 full scale and zero Calculate Takes the acquired data and calculates the derived calibration coefficients - will not proceed unless there is no more than one zero in the applied pressure text boxes Clear Clear the current calibration test data to zeroes, also clears the calibration controls Save Test Save the current calibration test data to a file - defaults to the current data directory Load Test Load the test data from a previous calibration - defaults to the current data directory Exp. Test Export the current calibration test data to a comma delimited text file Temperature Cal. When checked enables temperature tabs 2 and 3 for a 3 temperature calibration. Unchecked only temperature tab 1 is available to the user and the software will calculated coefficients for a non temperature calibration Page 18 Live Values Unchecked, the live values from microDAQ are inhibited from overwriting existing values in the calibration controls. Use when loading a previous test for examination or recalculation of coefficients View channel Select the channel that supplies the values displayed in the calibration controls Remote Coefficients C0 - C3 Calibration coefficients uploaded from microDAQ for the selected channel Read Remote Upload and read the current calibration coefficients from a connected remote device (microDAQ) Compare to Local Compares the current set of microDAQ coefficients with those last calculated or loaded to local memory, and provides a result of identical or not Channel Select the channel to view its current calibration coefficients Local Coefficients C0 - C3 Calibration coefficients last calculated from a calibration test or loaded from a previous calibration Send and Burn Download all local coefficients to microDAQ then write them all to its EEPROM Copy CANdaq Copy the current set of microDAQ coefficients to the local memory - allows storing of calibrations from a microDAQ or copying a calibration from one unit to another without recourse to original files of either calibration data or coefficients Channel Select the channel to view its local calibration coefficients Clear Set local coefficients to zero and clear the coefficient text boxes Calibration Load/Save Calibration file Shows the path and filename of a calibration file if loaded Open Load a file of coefficients from a previous calibration - defaults to the calibration file directory Save As Save the current local calibration coefficients to a file - defaults to the calibration file directory Export Export the current local calibration coefficients to a comma delimited text file - defaults to the current data directory Table 5.8, 'Calibration' Tab Control Functions. Figure 5.9 , 'Calibration' tab 'Action' buttons. Page 19 Control Function 'Read Remote' Upload the calibration coefficients currently stored in microDAQ to the software. 'Compare to Local' Compare the values of coefficients uploaded from microDAQ to those in the local memory, ie those either newly calculated or copied from another microDAQ . 'Send + Burn' Download the coefficients in the local memory to microDAQ and burn them into EEPROM. 'Copy Remote’ Copy the coefficients over from the microDAQ memory to the local memory. 'Clear Local' Set all the local coefficients to zero. ‘Check Cal.’ Compare the local and microDAQ calibrations held in memory, and confirm if identical. ‘Set Span’ Set the span of the linear calibration – confirms the value of pressure that has been set up as the span value is being applied to the sensor. ‘Reset Linear Cal.’ Resets the linear calibration to (+ 0) x1 ie no offset, unity gain. Applies ONLY to the current linear calibration, ie the DTC calibration if using a DTC scanner. Table 5.9 , 'Calibration' tab 'Action' button functions. 5.5. 'DTC Information. The 'DTC Functions' tab gives the user access to an amount of information regarding the attached DTC scanner. The scanner voltages for temperature and excitation may be read and the position of the calibration shuttle valve determined as either being in 'RUN' or 'CAL.' mode. Also, the information contained in the scanner header may be uploaded and displayed. Note that the value of the parameter read from the scanner (ie temperature, excitation voltage and particularly valve position) is valid only for the time that it is read. To reduce the likelihood of a misleading reading being displayed, the displays are cleared after a number of seconds. Figure 5.10, 'DTC Information' tab. Page 20 Control Function 'Temperature (V)' Click '>>>' to read the current temperature voltage from the scanner. 'Excitation (V)' Click '>>>' to read the current excitation voltage from the scanner. Calibration Valve Position Click '>>>' to read the valve position as 'RUN' or 'CAL'. 'Range' Shows the floating point value for the range contained within the scanner. 'x3 derange' Shows the floating point value for the sensitivity derange constant contained within the scanner. 'Channels' Shows the floating point value for number of scanner channels. 'Read' Uploads the data header from the DTC scanner, splits out the information and displays scanner full scale, the number of channels and the deranging factor. Also shown are the scanner model, serial number and date of manufacture. Header Gen Added for future enhancement. Slow DTC comms Retained from CANdaq Mk3 for historical purposes – not currently used Table 5.10, 'DTC Functions' tab control functions. Page 21 6. Service and Calibration 6.1 Service There are no user serviceable parts inside the instruments. Should any difficulties be encountered in the use of the microDAQ, it is recommended that you contact Chell Instruments Ltd for advice and instructions. 6.2 Calibration Calibration is recommended on an annual basis and Chell Instruments Ltd. Provides a fully traceable facility for this purpose. 6.3 Adjustment There are no user adjustments in the instrument. The user is strictly forbidden from removing the covers without invalidating Chell’s obligations under both Warranty and COSSH. 6.4 Cleaning A dirty instrument may be wiped clean with a soft cloth that has been sprayed with a proprietary ‘foaming cleaner’, then wiped dry immediately. Under no circumstances should the instrument be wetted directly or left damp.