Estop circuit question

bigrthanur

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Mar 2007
Location
Ohio
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Hello again!

I am looking at using the new AB 440RD22R2 next gen safety relay with Dual inputs and 2 outputs. I want to have one input be a non contact gate switch and one input be an estop pushbutton. The machine (call it machine #1) with be interfaced with a robot cell(call it machine #2)

What I need it to do:

1. When the non contact switch is broken only shut down outputs from Machine #1.
2. when an estop is pushed shut down machine #1 and Machine #2.

Can this be done only using one Relay? And how? I only can seem to figure it out by using two but I think there should be a way to only use one of them?

Thanks in Advance.
 
While it's typically difficult to answer questions about circuits and machines one cannot see for one's self, the fact that you are wanting to do something less-than-straight-forward with a safety relay, I feel comfortable saying "No", you can't do that. Even if you found some way, I feel certain you would be compromising the safety aspect of the relay's design.

In my opinion there is no acceptable reason to cut corners or to try to do-more-with-less when it comes to safety circuits. You are messing with people's lives and limbs here. It simply isn't worth it.

Steve
 
I believe that you would actually need two circuits.

E-Stops are not Process-Stops. They are hardwired circuits that remove energy and ceases function. In order to reset, there must be a secondary action (first being reset of the E-Stop button).
 
Whilst I am not familiar with this particular safety module, generally the 2 inputs you refer to on safety modules are actually 2 channels intended for connection to 2 separate contacts on the safety switch or push button. The 2 channels are monitored so if only 1 channel is broken and then unbroken the safety module will see this as a malfunction and thus lockout. The 2 outputs generally work in tandem also. If you need to have multiple zones you must use multiple safety modules and circuits, or consider a programmable system if cost allows.
 
Liam is right, the safety relay looks that both inputs are broken. It also somehow looks at the resistance and you must use 2 NC inputs per estop. There is no way of tricking it that I know of and believe me, we tried everything we could think of a couple of months ago.
 
1. When the non contact switch is broken only shut down outputs from Machine #1.
2. when an estop is pushed shut down machine #1 and Machine #2.
Click to expand...

What you describe requires two circuits, but it is easy to coordinate them as you have it.

Machine 1 has in its safety relay input circuit(s) contacts from both the non-contact switch and the safety relay output contacts from Machine 2.

Machine 2 has only its e-stop push button contacts in its safety relay input circuits.

Paul
 
Hi

I have used this new relay and it can take in two different Inputs both dual channel. So it will work for your inputs and frI'm what I remember ( I will confirm tomorrow) it will also work the outs as you wish. Normally I would also have use two safety relays one for EStop and one doors but this new realy acts as two safety relays and also allows extension modules I think

Double check in the morning

Donnchadh
 
In Publication 440R-SG001C-EN-P – October 2012, page 3 lists the 440R-D22R2 as only having two outputs but looking at the diagram they are controlled by only one set of internal relays, so you would need 2 units to do what the OP wants to do.
 
Last edited:
Like others said you will need 2 units...if op does not need the control reliability that a safety relay should be used for like using 2 channel inputs and 2 channel outputs he might as well just use common relays or contactors but that wouldn't be right eh?
 
clank said:
Like others said you will need 2 units...if op does not need the control reliability that a safety relay should be used for like using 2 channel inputs and 2 channel outputs he might as well just use common relays or contactors but that wouldn't be right eh?
Click to expand...
Correct this will need to be a control reliable circuit.
 
Donnchadh said:
Hi

I have used this new relay and it can take in two different Inputs both dual channel. So it will work for your inputs and frI'm what I remember ( I will confirm tomorrow) it will also work the outs as you wish. Normally I would also have use two safety relays one for EStop and one doors but this new realy acts as two safety relays and also allows extension modules I think

Double check in the morning

Donnchadh
Click to expand...

I was thinking that what you say is correct but from the documentation that came with the relay I do not see how it can be done. If you could verify this I would appreciate.


Thank you
 
I have not used this device, but looking at the documentation I don't think you can do want you want with one relay. You need two separately-controlled outputs for what you call machine#1 and machine#2, but the outputs on this relay look to be driven together.

45605.gif


It appears that you can specify how the two dual-channel inputs are logically combined, but the result is always one redundant signal.

44421.gif


Someone please correct me if I'm wrong.
 
HI

As per the picture the unit can take the different inputs
but you will need a extision module to get the outputs to act as you want them, please see second picture.
This does mean you need two units, one being the extision module.
Sorry about that but I could not remember how the outputs worked.

Donnchadh

e_stop.JPG e_stop2.JPG
 

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