Encoder - What types are compatible with Gocator sensors?

Encoders provide an accurate displacement reference that allows Gocator 1xxx and 2xxx series sensors to acquire data at consistent distance intervals. It is important to use an encoder in a Gocator system when constant motion cannot be guaranteed and helps to minimize impact of acceleration & deceleration on scan data quality even when constant velocity is present. Depending on the LMI hardware available, different encoders can be used.

Broadly speaking, Gocators are only compatible with Incremental Encoders. Gocators are not compatible with Absolute Encoders.

Every encoder has a different driver type, which refers to the electrical signal characteristics the encoder uses to communicate to its connected system. The table below shows which encoder driver types are compatible with specific LMI hardware. 

Gocator Compatible Encoder Types

• Master 100 uses an I/O cord for encoder signal propagation, which gets decoded in the sensor. We support only quadrature-differential encoder via this interface.

  • Link to IO terminals and required differential voltage

• Master 810 and 2410 support the following types of encoder signals: Single-Ended (5 to 12 VDC, 12 to 24 VDC) and Differential (5 to 12 VDC, 12 to 24 VDC). On Master 810/2410, we decode the encoder signals on the Master and then propagate the count piggybacking on the sync signal over Power/LAN cord. There we support both quadrature and single-ended encoders. .  

  • Link to wiring information

     

Example - The Gocator Legal For Trade System specifies the following encoder for use:

LMI Part number: 301251 - ENCODER model TR3-U5B-3000NV1RHV-SMK-L5CE and open-ended harness

Learn more about LMI's legal for trade system - Link

Why are differential voltages negative? - Link

“Differential Threshold Voltage” is the required threshold between A+ & A-, and B+ & B-.

Unlike single-ended signals, differential signals are transmitted in parity. That is, instead of a single conductor referenced to ground, two conductors, referenced to each other, transmit data. The digital driver still drives two voltages, as in the single-ended case. The receiver, however, interprets the signals based on the voltage difference between the pair of signals — not on a reference to ground. For the differential digital signal to be interpreted as a binary zero, the signal must be less than its complementary signal by more than a particular value. 

This is a high level explanation of why the differential threshold voltage is negative.