SLC5/03 MSG-instruction - problem with strings

Hi all,

I'm trying to communicate strings between a CompactLogix and an SLC5/03.

To make this possible I'm using SLC mapping to map the string (standard 82 character string) in the CompactLogix as ST50. The CompactLogix has DH485 address 2.

In the SLC5/03 (DH485 address 4) I have programmed a MSG instruction with the following parameters:

This controller:

• Communication command: 500CPU Read
• Data table address: ST100:0
• Size in elements: 1
• Channel:1

Target device:

• Message time-out: 5
• Data table address: ST50:0
• Local node addr. (dec): 2
• Local / Remote: Local

I'm getting an error message stating "Local processor detects illegal target file type.".
Within the same program I'm also reading 5 integers in this way and that seems to work fine. What am I doing wrong?

Kind regards,

Maybe your MSG is attempting to write to non-existent file
in destination PLC or outside file boundaries?

No. The CompactLogix has a mapping for file 50 pointing to a single standard STRING (82 characters). The SLC has ST100 datafile containing one STRING. Yet it seems impossible for the SLC to read the string in the CompactLogix. From the documentation I figure it should be possible.

Kind regards,

Jean Pierre,

From what I gather, you cannot do a direct message read/write between the SLC's and the CompactLogix for string type data. You need to exchange it in integer format and then copy the integer file to a string file, or vice versa, to convert back. The following link has a Word doc attached that will explain this a little better.

http://domino.automation.rockwell.c...B60FBFAB475417CA85256D5F005E7CEF?OpenDocument

Hope this helps.
Jeff

Jeff,

thanks for the reply. Pity you didn't answer this question some 20 minutes earlier. Thursday one of my trainees put this question under my attention. I told him PLCs.net would give us an answer within 24 hours, but the answer came 20 minutes late. Despite that a very fine example of how well this forum works :site: .

Ultimately I did it almost exactly the way it's described in that link. The only difference was that I wrote the string from a SLC5/03 to a CompactLogix over DH485 in stead of writing from a CompactLogix to a SLC5/05 over Ethernet. I also noticed I had to swap the individual bytes in the integers to get the string over correctly.

Thanks anyway,

I know zip about the CompactLogix, but when I've gotten similar messages in SLC to MicroLogic or SLC to SLC comms it was because the size of the array or data file wasn't large enough to accommodate all the data points. Maybe this is your problem.

(PS - sorry I missed the deadline!)

Jean Pierre,

I'm glad I was able to help. Tell your trainees that if it wasn't for the unbelievable amount of spam that I have to clean out of my Inbox every day, I may have gotten in under the wire.

Jeff