Message string from Compact Logix to Micrologix

[wilkerson29847]

Good afternoon everyone.

I am in need of some guidance. I need to message a string value from a 1769-L30ER to a ML1400. How do you go about doing that since you can't directly message a string data type to ML? I was going to use a STOD conversion and then message it over as a L data type in the ML and then use an AIC instruction in the ML to convert it back to ASCII but that doesn't allow me to use an L data type as the source. Not sure that would do what I needed it to do anyway. Is there an easy way to message this information over to the ML?

 

[Ken Roach]

How long is the data in the String ? Does it always represent an integer value, and how large is that value ?

If it's a String that doesn't always represent an integer number, then you will have to decompose it into an INT[x] array that includes the Length and a transaction sequence number, then re-assemble it out of Integer N-file elements in the MicroLogix.

If it's an integer, then the STOD on the CompactLogix side and AIC (Integer to String) instruction on the MicroLogix side should do the job, but only if it's a 16-bit signed value (-32768 to +32767).

 

[wilkerson29847]

The string data size varies between 5 and 20 characters and includes letters and numbers. That is why I am having a problem figuring out how to message the data over to the ML. Honestly, I'm not sure of how to do the transaction sequence number you mentioned or how to reassemble it in the ML.

 

[Ken Roach]

Like this on the CompactLogix side:

 

[Ken Roach]

I don't have a MicroLogix handy to examine what happens on the other side.

Here's how the "packaged for sending in an Integer data block to the MicroLogix" tags should look on the CompactLogix side:

 

[Ken Roach]

I can't be certain the characters come out in the right order on the MicroLogix side, but the principle is to:

1. Detect the change in the TSW so you know new data has arrived
2. Set the Length of the target String data table element
3. Copy the characters out of the N file to the ST.Data file.

 

[Ken Roach]

A thought: I didn't account for the possibility of leftover odd-length characters in the array when the string changes size. Add logic to fill the INT[x] tag in the CompactLogix with zeroes before you copy the string data into it.

 

[L33er]

Swap the bytes before copying to Source_INT[].

 

[wilkerson29847]

Ken

Thank you for all of the guidance! I got to work this morning and started working on this again but I am getting an error in Logix 500 when I go to validate the program. See attached screen shot

 

[wilkerson29847]

L33er,

What bytes are you talking about swapping?

 

[drbitboy]

Ken

Thank you for all of the guidance! I got to work this morning and started working on this again but I am getting an error in Logix 500 when I go to validate the program. See attached screen shot

Cf. https://literature.rockwellautomati...documents/rm/1763-rm001_-en-p.pdf#G24.1050332



[Update: whoops, never mind.]




[...]

 

[drbitboy]

I've found other threads where this works with 1400 but not 1100; is Logix 500 configured for 1400?

 

[OkiePC]

L33er,

What bytes are you talking about swapping?

You would need to swap the bytes within each word of the string data.

As for your program not verifying, I can get it to verify (even with an odd length) in a Micrologix 1400 program I had handy. I am not sure if it would verify for a Micrologix 1100. There are some not so subtle differences in those two seemingly similar models.

Note that the CPW Length (unlike regular copy) is based on 16 bit words, not the data type of the destination.

 

[wilkerson29847]

I was digging through some documentation and found the following blurb in reference to the CPW instruction.

"The ST file type is supported in MicroLogix 1400 Series B processors."

Unfortunately, I have a MicroLogix 1400 Series A. Just to test it out, I changed the processor to a Series B and then it validated.

Back to the drawing board I guess.

 

[drbitboy]

Back to the drawing board I guess.

Can you do this?

MOV N18:2 ST14:5.DATA[0]
MOV N18:3 ST14.5.DATA[1]
...

Ugly, even if FAL or loop is used, but it may work.


Or perhaps do the conversion to 16-byte INT on the CompactLogix side, and MSG directly to .DATA[0:41] i.e. clone Leader directly into his suit?