temperature control by plc

hi

I have programmed PLC to control weighing system by connecting amplified load cell output to the analog module connected to the PLC then Scaling analod input in the ladder diagram.

I want to know when controlling temperature is it possible to use the same analog module and scaling or a special temperature module is required and if this is true, do I need to make scaling or the temperature module gives the temperature direct?

You will use a temperature probe (pt100, thermo-couple type j,k) depending on the application. Get a probe that has a 4-20mA or 0-10V transmitter on it and connect to an analogue input card that can read 4-20mA or 0-10V. The transmitter will have a full scale value on the nameplate telling you at what temp it is at 20mA or 10V. More help can be given if you give more information

When dealing with analog signals you will always be required to scale the electrical signal into whatever engineering units are appropriate.

The analog input card needs to be compatible with the field sensor device.

Thermocouples (T/C) need cold junction compensation and linearization, so T/C's need a specific thermocouple analog input.

RTD's need excitation current and so RTD's need a specific resistance or RTD input.

"transmitters" convert low level sensor signals to various standard industrial signals, like 4-20mA, 0-20mA, 0-5Vdc, 1-5Vdc. Hence an analog input card that takes these types signals can have a variety of sensors connected, since the electrical signals are all similar.