SLC Rack Connect to A control Logix plc

Donnchadh

Lifetime Supporting Member
Join Date
Jun 2002
Location
Ireland
Posts
1,004
Hi all

I am looking at a project ,and as part of it I have to remove
a slc 5/05 processor.The slc rack has two,eight channel analogue
input cards and the rest is digital in and output cards.
We are adding in a control logix so my question is,what is the best
way to tie into the slc rack.Is it by adding a DH+/RIO card in thr control logix and a SN card in the SLC rack.I have seen posts here
about PLC 5 and using the rack as a rack in the control logix program.Is this correct and is there a way to set it up as a devicenet rack as we have a devicenet scanner in the control logix.

Thanks for taking the time to read this.

Donnchadh K.
 
Depending on your available resources, the solution can come in many different forms...

1. Totally replace the SLC hardware with ControlLogix/FlexLogix/CompactLogix hardware.
2. Do the RIO thing. Remember the scan rate and communication rate of RIO.
3. Utilize the SLC5/05 processor as an IO handler.
4. ???
 
Why not leave the 505 and use ethernet to communicate with it, Instead of buying a DH card and a SN card - then your kind of regressing from ethernet to slow DH
 
DBLD99 said:
Why not leave the 505 and use ethernet to communicate with it, Instead of buying a DH card and a SN card - then your kind of regressing from ethernet to slow DH

That was my thought. It depends on bandwidth though.
 
If you want to use the SLC rack as remote I/O to the CLX processor, you will need a DHRIO card in the ControlLogix chassis, and a 1746-ASB (NOT a 1746-SN) in the SLC rack. This is crucial.
The 1746-SN card is a scanner or Remote IO master, where the ASB module is an adaptor. The ASB is used in the remote rack to connect to an RIO scanner.
 
Hi All



Thanks for the reply.I think I will go with leaving the processor

in and just map the I/O across ethernet.

Does anyone see anything wrong with this.



Thanks again

Donnchadh K.
 
Yes, there is (potentially) something wrong with that.

You will have to roll your own determinism to use the SLC ethernet channel without worrying about what might happen if I/O don't get updated for a few seconds or longer.

Be sure to carefully study the timeout periods, and/or add your own heartbeat logic to shut things down and test it by unplugging the cable.

The worst thing about your situation is that A/B still has not put forth the effort to write firmware for the 1746 controlnet adapter to make your hardware controllable via controlnet.

Apparently they have no intention of doing this or it would have happened by now. I am sure they are selling a lot of controllogix cards because of the poor choices they give us for controlling 1746 I/O with logix.

Be careful
Paul
 
OkiePC is correct. All you can do between a SLC 5/05 and a ControlLogix over Ethernet is messages. If you are using any 'critical' commands over this link you need to build in your own error checking (I vote for the heartbeat idea, by the way) and response. This would mean the SLC would need to be effectively free-standing as far as local functions are concerned. The ControlLogix would just issue very high-level commands.

What I would like to see in the 1746 family is to have Ethernet I/P slave firmware added to the SLC 5/05. Set it up like a PLC5 Remote I/O slave but over Ethernet. But I agree with OkiePC. Just like the ControlNet card, I doubt we will ever see it.

Keith
 

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