If you’re monitoring a bridge or automating a machine, a high precision sensor is a great solution, but it’s no good if the output signal can’t reach the data logger. Depending on what you need to measure and what environment you’re in, determining how long your cable must run can be crucial.
High precision sensors offer three common output types: analog, digital and current and each one can serve a certain purpose based on your application
Capabilities of Voltage Output
Analog output is typically used for applications that do not require long cable lengths since voltage is susceptible to noise interference from vibration and RF waves. A thicker, shielded cable can be used to resist noise and allow cable lengths to run to 50 feet or more. This comes in handy for industrial manufacturing applications where is longer cables are needed, but there is a lot of outside movement and vibration. Some standard options are 0-5, ±5V, 0-10V, ±10V or 0.5-4.5V
Capabilities of Current Output
Current output is more immune to outside interference which means it can run through cable lengths of 4,000+ meters. For really long lengths, a shielded cable may be necessary to resist outside noise and vibration. This is used for putting a sensor in hard to reach places such as structural monitoring, retaining walls, slope stability, volcano studies and platform leveling and positioning. The standard option is 4-20mA output.
Capabilities of Digital Output
Digital output can provide a variance of cable lengths based on which signal is used. The maximum length for RS232 output is 15 meters, which is fine for industrial automation and testing. RS422 and RS485 are capable of up to 1,000 meters of cable distance giving you more ability for things like structural monitoring. Other options are also available for some models, such as UART TTL and Ethernet interface.
Which sensors offer these output options?
Many sensors offer multiple output options so that you can use the specifications of one model, but with the choice of two or three output types. Force balanced sensors that offer more than one output option include the LCF-2330, LCF-300, RMI, SMI, LSOX, DXI and DXA. MEMS sensors offer analog, current and digital output types as do the 700 series, 800 series and 900 series electrolytic tiltmeters.