So i can series wire the 22 switches to a single safety relay with one set of the contacts on each sensor and then use the other set of contacts on each sensor to its own input of the PLC which will allow each door its own output alarm or lamp?

One thing to keep in mind if doing it that way is if the open door indicators are using physical outputs of the PLC is to ensure the power to them is kept live when the safety relay operates. Depending on how the safety relay is configured, as normally it shuts off output and control device power.
It is common to leave the input power on.
Max.

 

You did @MrChips apologies I'm just not sure yet how many contacts are in these sensors

 

You did @MrChips apologies I'm just not sure yet how many contacts are in these sensors

3 sets according to datasheet. 2NC and 1 NO

 

Then which one will I give to the input of the plc the NO or NC?

 

Then which one will I give to the input of the plc the NO or NC?

"closed when door is shut"
I don't know if they're calling that NC or NO. I would test with a meter

 

Not trying to hijack the thread but keep in mind that if the PLC is actually controlling the safety area and there is a chance someone could force the inputs in the logic to bypass them then you need to look into using a safety PLC instead. Most use 2 inputs per switch to ensure no hardwired jumpers are present, the program is protected so copies can't be used other than to monitor the logic, no online edits or forcing, etc.

Actually seen installations where some idiot thought it would be a good idea to have the safeties soft-wired into logic so it would be "easy" to jump them out to keep from loosing production.

If it's just to monitor the switches have at it.

 

Thanks Neuhauser I was actually looking at safety PLCS but I can't budget for it. Machine definitely needs a Plc but I'm open to ideas on the safety side alright more the merrier while keeping it as basic and safe as possible

 

Why not use the N.O. series string (closed contact when doors closed) and input to a Safety Relay to control the motive power devices, and use the other contacts just for indication purposes back to the PLC.
Max.

 

So keep them all in series?

 

Series for the safety circuit, but take them back individually to the PLC via the aux contact if you want a distinct door fault notification, There are a few ways to do it in the PLC , one is if there is a general start P.B. or whatever initiates the operation, and after a time delay allowing all doors to close, indicate a particular door(s) if not closed.
Max..

 

Ok because there is a reset button too that holds out when a door is opened or e stop pressed which then pulls back in the safety relays

 

But I assume that would not indicate an individual door, just any one or more.
If the safety relay is already there then you just need the individual door open detection holding off the restart, if I read that correctly.
Max.

 

Yeah that's right Max. So it's back to one side of the contacts on each door sensor going back to plc for individual detection?

 

De ja vu

 

Yeah that's right Max

Are you still leaning towards the Alpha 2, it is more along the lines of a Smart Relay but you should be able to use the display as a annunciator for the door error condition.
If you are controlling more of the machine then the FX series might be a consideration, but would require a Maple Sys. OIT display.
Max.

 

Well i was leaning towards an FX Mitsubishi model because the alpha wouldn't be big enough for all the inputs for the doors but after looking t machine again some of the areas have up to 4 doors on the same alarm light so i was thinking i can keep that and just go with the reduced inputs and larger zones. Also could i not put the safety relay back to the PLC via an input to through the reset button and the output switching on the coil?

 

I thought the Alpha comes with 16 inputs? also expansion is available, unless you are thinking of controlling other parts of the machine.
I would have thought for expediency in trouble shooting or displaying relevant information, a line monitoring each door would be preferred?
Not sure of what you mean regarding the Safety relay?
Max.

 

yes sorry i found the alpha with the 16 inputs. i mean how about if i was to give the reset button its own input to the plc (which is resetting the safety relay) and then let an output of the PLC switch it back on once normal conditions are met

 

What is the Safety Relay part No. if it is existing, if not, do you have one in mind?
https://www.google.ca/url?sa=t&rct=...sg=AFQjCNF4XB8JDvMERLHDtcNOOboveqbJDg&cad=rja
Max.

 

http://ie.rs-online.com/web/p/safety-relays/1930520/

That is the link to the realy currently in use there are actually two of them in series inside the machine