For our PLC OMC 8000 range we selected module architecture. At the heart of the system there is the main module which can be accompanied by up to 31 expansion modules. These can be both nearby, or at a distance. The total combined distance is up to 40 m while the maximum data flow is still maintained. Communication is realised using the CAN interface. It needs to be remembered that the higher the number of expansion modules, the higher the demands on the communication line there will be. The main module can be powered by 230 V or 24 V. It contains three digital inputs, which react to the power supply voltage. It also comes with six versatile inputs, all of which are electrically isolated (sharing a common ground terminal amongst them), from outputs and power supply. These can process the following signals:
• pulse up to 30 V
• pulse - contact, NPN open collector
• analogue, voltage up to 30 V
• analogue, current up to 20 mA
• analogue, Pt 1000, Ni 1000, Pt 100 (only two inputs)
• analogue, T/C - B, E, J, K, L, N, R, S, T, XK
• analogue, KTY81-2xx

Versatile inputs can also be used as two full quadrature inputs for the use with quadrature encoders where two input signals come with a 90° phase shift + zeroing pulse. One pair can be used as RS485 for communication with external devices such as numerical or text displays, operator panel etc.

The Module can contain up to 5 digital inputs (either relays or open collectors). It can also contain one analogue output, but in such case the number of digital inputs is only 3.