Profibus

I am using an allen bradley slc 505 I have a profi bus card in slot 2 hooked to SMC solenoid valves, when i do an estop the valves continue to function they do not drop out. I can not cut power to the valves because it also controls the comms. Any ideas?

Thanks Jim Cav

when i do an estop

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Which circuits are cut by your E-Stop ? Is it the SLC-5/05 power, or just the output power to I/O modules ?

jimcav said:

I am using an allen bradley slc 505 I have a profi bus card in slot 2 hooked to SMC solenoid valves, when i do an estop the valves continue to function they do not drop out. I can not cut power to the valves because it also controls the comms. Any ideas?

Thanks Jim Cav

Click to expand...

You may be hooked. I see the issue, cut the power that is supplied to the solenoids, and the comms section dies as well.

Maybe the estop can be hardwired to a solenoid that supplies air to the block

Ian

I'm sure now that I do not understand the question.

Maybe what Jim means is that he "e-stops" the SLC-5/05 by removing power to the controller, which causes the Profibus master to stop scanning. The Profibus slaves (the SMC valves) apparently "hold last state" and stay in whatever state they were in when the communication stops.

Essentially, Jim is asking the Profibus network to act as a functional E-stop.

Or maybe I'm getting it wrong. Jim, could you expand your post into a more specific set of questions ?

Ken Roach said:

I'm sure now that I do not understand the question.

Maybe what Jim means is that he "e-stops" the SLC-5/05 by removing power to the controller, which causes the Profibus master to stop scanning. The Profibus slaves (the SMC valves) apparently "hold last state" and stay in whatever state they were in when the communication stops.

Essentially, Jim is asking the Profibus network to act as a functional E-stop.

Or maybe I'm getting it wrong. Jim, could you expand your post into a more specific set of questions ?

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Typically when we have a true MCR circuit all the field I/O power is cut when the MCR drops out.

The SMC Profibus solenoid valve block has two connections to it, one for the Profibus cable, the other for the block power. If the MCR drops out the block power, the Profibus comms will fail as the block is no longer powered.

Rockwell was smart with the Kinetix Servo drives and the LIM module with three connections. One for the Sercos, one for control power and another for bus voltage. The MCR circuit would always drop out the bus voltage keeping the electronics and the communications alive.

This is not the case with the SMC Profibus block. In hind sight, the block should have Profibus power and I/O power connections, so that an MCR can drop out the I/O but keep the comms alive.

In this current case, the MCR may need to drop out the air supply to the solenoid block

profibus

curlyandshemp you hit the nail on the head, i have even tried the s11 and s12 words to dissable the slc slot but when i bring the slot back the profibus card stays down i have to cycle key switch on the processor to get the card to come back up. I talked to woodhead about this and they said all they have in the m files is statis. No control.

My next question would be: do you think the SMC valves would have some smarts in them were i could send something over the profibus?

My only thought know is to put a bit in front of every output in the program and is this legal.

Also what if I took the whole word of outputs and moved 0 into the word, what would the results be?

jim cav

jimcav said:

curlyandshemp you hit the nail on the head, i have even tried the s11 and s12 words to dissable the slc slot but when i bring the slot back the profibus card stays down i have to cycle key switch on the processor to get the card to come back up. I talked to woodhead about this and they said all they have in the m files is statis. No control.

My next question would be: do you think the SMC valves would have some smarts in them were i could send something over the profibus?

My only thought know is to put a bit in front of every output in the program and is this legal.

Also what if I took the whole word of outputs and moved 0 into the word, what would the results be?

jim cav

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If you can't electrically isolate the outputs then you have to pneumatically isolate them. A hardwired solenoid that supplies air to the bank may be the only solution in this case.

Ian

good answer i will look at using a dump valve.

thanks for the help

jim cav

jimcav said:

good answer i will look at using a dump valve.

thanks for the help

jim cav

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safety relay

this is the safety relay we use. Controls an MCR relay and also provides an input to the PLC so the logic can also kill the outputs under program control

Ian