exchange devices

[amendoza]

Hello friends,

I hope you're all doing well. I'm reaching out because I find myself in need of some assistance with a situation. As someone new to programming, I recently undertook the task of creating a lengthy program. However, there's a concept I failed to consider and I could really use your expertise on this matter.

You see, I've been working with input and output expansion modules, and what caught me off guard was that these modules automatically assigned addresses within a certain range. For instance, X0 was assigned to X15, and X20 to X34. Regrettably, I didn't anticipate this, and I ended up assigning the new device numbers to these expanded modules.

I'm wondering if any of you have encountered a similar situation or if you have any advice on how to handle this issue. I'm open to any insights or suggestions you might have. Thank you all for your time and assistance.

[JDennis]

Need some more info.

What PLC are you using?

Whenever I have added I/O expansion modules (FX series) The additional I/O points are automatically added and don't require being assigned new device IDs.

 

[Crossbow]

Extension modules have addresses assigned automatically, and it always starts at a 0.

FX modules are addressed in OCTAL, so 0-7, then 10-17, then 20-27, etc.

Q/R modules are addressed in HEX, so 0-F, 10-1F, 20-2F, etc.

This is clearly explained in the manuals for the PLCs.  You should have reviewed this information before assuming what addresses would be assigned.  You will have a lot of work to clean up anything you wrote before understanding this.

[Nightfly]

On 16/08/2023 at 9:31 PM, amendoza said:

I'm wondering if any of you have encountered a similar situation or if you have any advice on how to handle this issue

It’s very common for programmers to map inputs and outputs to internal memory (flags) and use these throughout their program rather than raw X and Y variables. If the input or output change then you only adjust one line. Also on PLC’s where the input value can actually change during a scan (Allen Bradley) it’s basically a necessity.