Micrologix 1200 1762-IQ16 IO connections

[Annaglory]

Hi all,

I have a doubt, it might seems silly though. I would really appreciate it if you could describe how to do this connection.

There is a 5VDC output from a chiller that indicates whether there is a fault present:

5 VDC = NO FAULT condition
0 VDC = FAULT condition

I am using Micrologix 1200 PLC, I want to connect this chiller fault voltage to PLC input (1762-IQ16 16 Input 10/30 V DC).

Since it is 0 & 5 V and the digital input card is 10/30 V,
I am wondering whether I can connect directly to IO card or should I convert that to 10 V? if so, how?

I have attached a portion of schematic and the specification details of IO card.

Thanks in advance.

ANNA

 

[bjh]

You'll need an interposing relay. The 5VDC from the chiller should go to the coil of this relay and you should run 10-30VDC through the N.O contacts of the relay to the input of the PLC.

 

[janner_10]

As above. Either use a relay with a coil voltage of 5v or have the chiller input into a Analogue Module and measure the voltage that way.

Relay is easiest and cheapest route though.

 

[Annaglory]

Thanks so much, Bjh and Janner_10 for your awesome responses.

Could you please suggest some of interposing relays which I can use for this application?

It would be great if you can also give me an idea, how connections should be done from chiller to relay and relay to PLC.

from the relay output, it will be one input to PLC? or two?

Thanks,

ANNA

 

[Bullzi]

Anna,
Welcome to the Forum by the way. You may need to find a 5V relay from a electronic component store like Newark, Allied or Radio Shack. More than likely it will also be a solid state relay as opposed to a mechanical relay. Since 5V is not a standard voltage that we use in industrial applications very often your choices are going to be limited. You can also build your own with a opto coupler if you are feeling up to it.

As for connections, As bjh said you just run the 5V signal to the Coil of the relay. Then run +24v from the power supply through the N.O. contacts of the relay and into the PLC input. Don't forget to run the -VDC from the power supply into the COM terminal of the PLC inputs. Be careful not to mix the commons from other power supplies.

Good luck.

 

[Annaglory]

Anna,
Welcome to the Forum by the way. You may need to find a 5V relay from a electronic component store like Newark, Allied or Radio Shack. More than likely it will also be a solid state relay as opposed to a mechanical relay. Since 5V is not a standard voltage that we use in industrial applications very often your choices are going to be limited. You can also build your own with a opto coupler if you are feeling up to it.

As for connections, As bjh said you just run the 5V signal to the Coil of the relay. Then run +24v from the power supply through the N.O. contacts of the relay and into the PLC input. Don't forget to run the -VDC from the power supply into the COM terminal of the PLC inputs. Be careful not to mix the commons from other power supplies.

Good luck.

Thanks Bullzi for your kind help. I understand that I should look for 5V dc SPDT relay but Could you please tell me what is the current rating of that relay?

 

[Bullzi]

If you are just running to a Digital Input you don't need more than 250ma (0.25A). That should be pretty easy to find.

 

[Annaglory]

If you are just running to a Digital Input you don't need more than 250ma (0.25A). That should be pretty easy to find.

OK Bullzi, Thanks.

 

[Annaglory]

Hi all

Kindly check the connections shown in the attached picture and I would really appreciate your feedback in this regard.

Thanks

 

[labeledas]

If you have 2 wires coming from the chiller system run them across your coil, it will probably have it's own DC Common/Return/GND check to see if the coil is polarity sensitive.

Then depending on how you have the card wired Sink/Source most likely a sinking input ie(24V to card and card com to DC supply common) 24V to 6T and T7 to whichever input you wish to use.

 

[Annaglory]

Thanks so much, labeledas for your guidance.

please tell me, what gauge size of wire I should use for this particular application. From chiller to Relay and from relay to Plc.

Thanks