Control Valve through Analog Input/Output - Beckhoff PLC

tech007

Member
Join Date
Aug 2010
Location
London
Posts
25
Hello,

I would like to control the valve through the beckhoff PLC. The valve operating range is from 0-10 volts and i have terminal EK 1100 (EtherCAT communication terminal), EL 3162 (Analog Input terminal)and EL 4104 (Analog Output terminal).

Can you suggest me how to control the valve through analog input and output terminal ?

How to programme analog input and output terminal ?

Thanks.
 
You can configure Ethercat Device in Twincat System Manager,and you need to insert module EL3162, EL1404, under this module you can link the variable with PLC variable
 
I noticed this is an old post, so the OP may be long gone. Anyway, for others interested,

What is the analog input (AI) measuring?

The very simplest approach is the AI measures an operator setpoint (potentiometer) and you simply output that to the analog output (AO), perhaps with a scale factor and offset. This makes the PLC just a feed-forward amplifier. The main reason you might do this is if the AI is in a control room and the AO is far away near the valve. In that case, the link could be via ethernet, which can be miles w/ fiber-optic. That is most useful if controlling hundreds of devices. You could also replace the analog pot with a PC input (mouse or joystick).

Most people want to control valve stem position, in which case the AI measures a potentiometer (or SSI, MDT, LVDT) on the stem as a feedback signal. The Operator inputs a desired setpoint (via PC or pot). The PLC runs a PID control loop to continuously adjust the output to maintain the desired setpoint.

If the setpoint comes from another outer control loop that is trying to maintain pressure or flowrate, it is termed "cascade control". That is very common and valve stem positioners are often built into the valve, especially pnuematic valves.
 

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