field simulation for PLC's

K

Thread Starter

koen

Hi all,

I working on a field simulation for PLC software.
I have created an OPC client to communicate with PLC addresses. For some it already works. Now I facing a problem with Modicon PLCs. I cannot seem to access the inputs (1xxxx and 3xxxx registers)

my question: Is there a way to write an value in the 1xxxx and 3xxxx addresses in Modicon quantum PLCs?

Thanx in advance,
 
In response to my previous post.

I know Inputs cannot be written.

But I've heard these input values can be pointed to the holding registers when designing the PLC software.

What kind of problems will I be facing when doing this?
and also, the input values CAN be written if this is implemented the right way, right?

Thanks,
 
C

Conrad Kinze

I have a question.
Why would you want to write to these addresses?

The PLC is setup so that they are read from the outside world. Any address that you can read can be mapped to another coil or register for reading.

In over 25 years I have found no application or reason to need to write to these addresses.

Perhaps, you are looking for a solution and this appears the only way to solve it.
 
V

Vladimir E. Zyubin

> I have a question.
> Why would you want to write to these addresses? In over 25 years I have found no
> application or reason to need to write to these addresses.

It seems to me Koen try to use a virtual controlled object (program simulator) instead of real plant. The approach is useful when the team try to use an iterative model of development, or when the team is just interested in the risk reducing during first running on the real plant by testing, or the team try to organise effective communication with the customer.. there is a lot of reasons to do so.

Alas, I have a feeling that the common practice is to test control algorithms with the real plant.

--
best, Vladimir
 
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