AligatorAmy

@kaiser_will Thank you for your reply.  I was sure that I have attached the "PLC4" file but if it is not there I resend it.  There are many other systems in the machine requiring better control and data logging. Effectively, I would need at least tens of heating controllers and many other PID units. 

Hi, I would like to provide the PLC control for a scenario where the temperature in a machine, heated by the two electric heaters, is controlled with use of 1 TCK and 2 s/s relays. Please see draft “plc4” sent attach. The TCK is fixed to the machine and is not in a physical contact with the heaters. Nominal temperature of machine is 200degC. The machine temperature tolerance is +/-2degC. This means that the heaters should be turned on when machine T drops to 198degC and turned off when T reaches 202degC.  For this moment I have created the start PLC diagram outlined on draft “PLC4”.  I am still learning PLC. Therefore, I would be very grateful for your opinion whether the PLC diagram shown on picture “PLC4”, in terms of the tools used (direct contact, direct coil, etc.) and their layout, is of proper design. I know that there is much more work needed to complete this task (e.g. set up of the variables, etc.). I am using Unilogic software. Please help. Regards