Model HI 1771-WS -Single Slot Weigh Scale Module

Communication between the module and the processor is bi-directional, using both block transfer reads (BTRs) and block transfer writes (BTWs). The module uses a byte in the output image table and a byte in the input image table. The module also requires an area in the data table to store the block-transfer read and write data.

Two independent firmware set points with separate preact and deadband are included to provide control capability. The module has two bi-color LEDs on the front to report its functional characteristics and an internal diagnostics switch to test if its input section is operating correctly.

A software file is included which links the HI 1771WS with Rockwell Software’s RSLogix™ 5.0 Version 4.0 providing graphic interface screens for on-line-configuration from a PC. The HI 1771-WS is used in applications such as batching, blending, filling, dispensing, flow rate monitoring and check weighing.

The Hardy Instruments HI 1771-WS is a single slot weigh scale module that mounts in an Allen-Bradley 1771 Universal I/O chassis. It reads weight data from strain gage load sensors and communicates this data over the I/O chassis backplane to one of Allen-Bradley`s PLC-5 family of Programmable Controller Processors. The HI 1771-WS module reduces installation costs as it needs no external stand-alone scale instrument, and provides a wired communications link to the PLC.

The HI 1771-WS conditions and digitizes the weight signal 20 times per second with over one million counts of resolution over a differential signal range of 0 to 30mV. It then transmits the selectable Gross, Net and/or Rate-of-Change data to the processor. This high resolution allows the module to tolerate large dead loads and oversizing of the load sensors while retaining a high level of usable resolution. The module supplies 10V of DC excitation to drive up to four 350 ohm load sensors, or load cells, associated with a single scale. It will support additional load cells with an external power supply.

Two independent firmware set points are included that provide control capability. Each have a separate preact to compensate for in-flight material as well as system response delays along with a deadband that compensates for potential relay chatter.

Two bi-color LEDs on the module`s front panel report its functional characteristics. Calibration can be performed in traditional ways (hard cal), or by our exclusive C2, Second Generation Calibration, which enables electronic calibration in seconds without test weights.

The HI 1771-WS has an internal diagnostics switch, which takes the sense and signal load cell lines and connects them to an internal resistance. If the weight reading with this resistance pulled in is stable and repeatable, the input section of the module is functioning correctly and the problem is elsewhere.

An Auto Zero Tracking feature allows the module to automatically ignore a material build-up on the weighing system within an adjustable zero tolerance. Automatically re-zeroing the module eliminates deviations due to accumulated ingredient build-up in the weigh vessel or on the scale.

Waversaver
The HI 1771-WS Weigh Scale Module utilizes Hardy Instruments` industryproven WAVERSAVER technology. WAVERSAVER eliminates the effects of unwanted plant vibration on a vessel during weighing by permitting the weigh scale module to "see" through the unwanted vibration signals - as low as 0.25Hz - while yielding a stable actual weight reading.

Application Data Software
The HI 1771-AD Weigh Scale Application Data Software contains a Dynamic Linked Library (dll) file. This file links the HI 1771-WS with Rockwell Software`s RSLogix™ 5.0 Version 4.0 and provides a graphic interface for on-line configuration of the module. The latest version of this software is downloadable from the Hardy Instruments web site.

Process Weighing:

• Batching/Blending
• Filling/Dispensing
• Level by Weight
• Check Weighing

Power
+5Vdc +/-5% from the 1771 I/O universal chassis
1,000Vdc minimum isolation from backplane logic circuirtry

Backplane Current
1.5A (maximum)

Inputs
Signal: -0.3mV thru +30.3mV dc
Sense: +/-5V dc +/-5% (10V dc +/-5% differential)
C2, Second Generation Calibration data

Outputs
Excitation: 10V dc +/-5% 1.5W (maximum)
Set point: 2 independent TTL level drive signals

Common Mode Rejection
100dB at or below 60 Hz (minimum)

Resolution
Reported: 1:985,000 (for 3mV/V load cell)
1:656,000 (for 2mV/V load cell)
Internal: 1:1,048,576

Vibration Frequency Rejection
0.25 Hz and above in 5 selectable steps

I/O Chassis Location
Any single I/O module slot

Compatible I/O Chassis
1771-A1B, -A2B, -A3B, -A3B1, -A4B, 1771-AM1, -AM2

I/O Chassis Keying Positions
Between 24 and 26
Between 32 and 34

I/O Chassis Addressing Mode
2-slot, 1-slot, or ½-slot (Note: 8-bit I/O image density)

Weight
1.6 Lbs (0.6kg)

Environmental Conditions
Operating Temperature: 0 to 60°C (32 to140°F)
Storage Temperature: -40 to 85°C (-40 to 185°F)

Relative Humidity
5 to 95% (non-condensing)

Weighing Modes
Net, Gross, Rate-Of-Change
Calibration
Electronic (C2)
Traditional (test weights)

Conversion Rate
20 updates per second

Certifications
UL, CSA

Connecting Cable(s)
HI 1771-C6, 6ft (1.8m)
HI 1771-C10, 10ft (3m)