how to connect NO or NC to DI module?

[krishna]

Hi all,
How to connect a NO or NC contact to DI module and how to simulate the same?

 

[Tom Jenkins]

Hi all,
How to connect a NO or NC contact to DI module

I use insulated copper wire and a screwdriver.

Seriously, this question(?) is impossible to answer. Are you looking for general guidelines, or (fear and trembling) are you in the process of actually wiring up a PLC? What is the brand? Are you looking at how an NC and NO contact are handled differently in the program logic? Are you looking at simulating with software, forcing the inputs in the programming package, or simulating a field device with actual contacts?

You need to define your problem and restate your question.

 

[jolio ST]

Hello Krishna.

I assumed you meant connect a relay (with either a NO or NC contact) to a typical DI module.
I have an image of an example contact from a relay to the input of the PLC. It's a very very rough sketch, but I think you might get a rough idea.ray:

regards
Sherine T.

 

[krishna]

Thanks Sherine.I got rough idea on this.

 

[Tom Jenkins]

Here is info from one supplier. You should get the manual information for the actual PLC and I/O card model that you are using.

 

[krishna]

Hi ,
Let us assume that I have a potential free contact,I have to connect this to one cahnnel of DI module.I will pass + 24 VDC from externally to the first end of the contact and I will connect the second end to one channel of the DI module.When the contact is NO I will 0 V on this channel and if it becomes NC then I will get + 24 VDC on that channel.I guess the common is internally shorted in the module.
Is it right?

 

[Tom Jenkins]

Hi ,
I guess the common is internally shorted in the module. Is it right?

IT DEPENDS on the model you are working with! Get the manual for the specific PLC you are working with.

Also, you seem to be confusing Open and NO and Closed and NC. Open refers to a contact that is "off" or not conducting, and closed refers to a contact that "on" or conducting. Normally Open (NO) and Normally Closed (NC) refer to contacts in their free state, that is the status they would have sitting on a table. NO contacts go from open to closed when an event (such as a finger pushing the button) causes the contact to change state. NC contacts go from closed to open when an event causes the contact to change state.

You wire both NO and NC the same, since the purpose of both is to signal to the PLC a change in status by conducting or not conducting voltage to the PLC's input.

 

[krishna]

Generally we pass + 24 VDC from SMPS to the field contact.The DI module reads the voltage in the respective channel.
Generally all DI modules reads the voltage but they will not generate voltage.
Is there any DI module that generates +24 VDC? So that one can use DI module itslef for generating + 24 VDC instead of using SMPS.