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Farm Electronics are pleased to introduce a Temperature Sensor Interface that can be used with any type of PLC logic controller.
Most PLC manufacturers provide and analogue temperature interface based on a PT100 type temperature sensor. Most users will know that these sensors are notoriously inaccurate for close temperature control applications. Also if a large number of sensors are required the cost of the PLC "add on" modules can quickly mount up.
The Farm Electronics PLC Sensor Address Interface may well be the answer.
Using this interface, 3 temperature inputs can be utilised. These outputs give a proportional 0-10v signal which can be connected to this type of input on the PLC. In addition one of these inputs can be multiplexed using a binary address from the PLC to read (scan) up to 16 individual temperature channels in turn. The interface uses Uni-Curve Thermistor sensors (10K @ 25C) which give accuracy down to + or - 0.2C.
The interface is supplied on a DIN rail mountable carrier which means it can easily be placed alongside a PLC in a control panel. The actual temperature sensor connections can be made using a Screw Terminal DIN Rail mounting card or via a panel mounting socket plate. Both these options connect to the PLC Sensor Address Interface via an IDC ribbon cable.
Connections to the PLC are via screw terminals. The Interface will run on a 24v DC power supply which is commonly used with the PLC anyway.
Temperature Range is -50C to +50C proportional to 0-10v range. ie: -50C = 0volts, 0C = 5volts, 50C = 10volts
To address the sensor scan 4 no. Relay or Transistor outputs are required from the PLC. A simple binary address will access each connected sensor in turn.