Thedra's Digital Monitoring Module is used by Thedra's TrueDPM software product to complete the instrumentation requirements of a typical older technology factory automation system. These type of systems do not have any comminucations ability to extract real time data from the machine as it is in operation. Thedra can use its DMM to accommodate 16 digital and 11 analog input signals. The module connects to a 4 wire RS485 bus that can be wired to a PC serial port, a terminal server, or a workstation serial port. Thedra's protocol driver allows up to 128 DMMs to the wires on the RS485 bus, assigning up to two 8-bit addresses per DMM on the RS485 bus. Most factory instrumentation requirements will require only one or two DMMs to pick up all the desired signals for monitoring.
The 16 digital inputs on the DMM can sense signals from 5 to 24 volts DC. Any higher voltages will require an isolator circuit to reduce the signal to meet the capabilities of the DMM input lines. Each digital input circuit is jumper selectable to accomodate different signals, such as switches, lamps, and LEDs. Input load on each circuit is 10k-ohm to ground to limit circuit loading on sensed signals.
Analog signals can vary from 0 to 5 volts DC. Other analog signals (10V, +/-10V, thermal couples, 4-20ma current loop, etc.) will need an analog adapter to interface to one of the analog channels on the DMM. These adapters are available from Thedra. Contact us for more information on these adapters.