PROFIBUS DISTURBANCES

[miltonzv]

I work in a crushing plant with crushers,vibrofeeders,pumps etc with a SCADA configuration.All these equipments communicate with the contol room through a PROFIBUS cable via a modicon PLC.The problem is in the network on checking for distubances there are loads of disturbances especially when we are running vibrofeeders which are controlled by Micromaster drives for their speed,other motors are not drive controlled hence they show no disturbances on startup.At one time these disturbances were tripping the whole plant once a certain vibrofeeder was run with another.the problem eased temporarily when we reterminated PROFIBUS cable connections to the drives.But still on monitoring the network there is alot of errors and disturbances that are still a great threat.What could be the cause of this and how can they be significantly be minimised?

Guru from Botswana

 

[itsmoked]

You say disturbance. Can you be more specific?

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[miltonzv]

I meant the flow of data within the communication cable that is the bits are being transmitted haphazardly,for instance the parity or stop bits are not defined

 

[powerjunx]

miltonzv,

Profibus again.. we do have the same. But, we illiminated the culprit.

Want to know what we did? We reduced the NOISE (disturbance) after we checked the communication cable grounding..refrain from GROUND LOOP. Although, we came to the point of nowhere after a succesive troubleshooting and Brain Storming.
As i said to my fellow "Dont give up, the problem never go out in the system, it's all there waiting for definite timing"

In your case, you already started troubleshooting the system in which you found that only at MICROMASTER, exclusive to the non-drive units.

1.)Do you used termination module that ties up to the DRIVE? Other way around, Drives are main source of NOISE since it generates HARMONICS to your system. Communication cable is sensitive to harmonics.
2.)Do you used the specified cable for the communication?
Avoid soldering between cable.
3.)Verify if the Cable runs or lay with the power cables, if does, avoid this installation. Try laying the cable perpindicular to the power cable.

This is just a simple steps.

 

[miltonzv]

Thats a better assessment,will check critical points that you mentioned especially the communication grounding and the noise levels from the Micromaster drives.which industry are you using the PROFIBUS?

 

[powerjunx]

miltonzv,
its siemens profibus-dp.