Siemens PLC and Encoder

[[email protected]]

Hi,

I am using a siemens PLC with two encoders and two motors in order to test synchronization. The motors worked correctly before but I had to add a new PLC to the rig. Now the values coming from the two encoders are much greater than with the previous PLC and the motors are not functioning correctly due to this. Any ideas as to why this may be?

Thanks

 

[jstolaruk]

Welcome to the Forum!
When you say "new", do you mean a new different model of PLC? A rundown of what the previous hardware was and what the new hardware is would help diagnosing the problem.

 

[[email protected]]

The old PLC model was siemens CPU 317-2 PN/DP while the new model is a siemens CPU 315-2 PN/DP. The code was uploaded from the old PLC and downloaded to the new using step 7.

 

[jstolaruk]

Ok, and what IO modules were used to read the encoders? Did you first compile and download the hardware configuration?

 

[[email protected]]

thanks for the help! They are also siemens, SM322 and SM321, I did. The rig also consists of another two motors in sync with two of the same encoders but using Profibus, these work perfectly as before with the new PLC, only the Profinet is failing.

 

[jstolaruk]

You'll have to configure each of the devices that are working on Profinet with their expected IP addresses. Downloading the h/w config to the PLC is not enough to do this.

 

[[email protected]]

I believe they already have been configured, each device has it's set IP address and the PLC shows no fault, the network appears to function aside from the values appearing in the inputs of the encoder when I monitor the code.

 

[jstolaruk]

Check their configuration now against what they were.

 

[[email protected]]

I've done that also, the configuration is the same aside from the PLC.

 

[jstolaruk]

What are the devices that the encoders are connected through?

 

[[email protected]]

Both encoders are connected through a siemens switch to the PLC.

 

[jstolaruk]

I think you're going to have to get someone more familiar with the project. There is a configuration that is not quite right (like a gain or scalar value) OR a scalar value that is applied to the raw readings by the PLC that does not match.