MSG instructions from L16ER to ML1100

[SpecialK87]

I know the answer is out there but I just can't find what I'm looking for. Maybe someone can point me in the right direction.

How do I set up a MSG instruction in a Micrologix 1100 to Read from a Compactlogix L16ER.

 

[Ken Roach]

The MicroLogix operating system doesn't know about the CompactLogix tag database; it only understands SLC/MicroLogix data table addresses.

The CompactLogix can emulate B, N, and F data tables by "mapping" INT or REAL array tags to a data table number.

In Studio 5000, select the Logic -> Map PLC/SLC Messages feature, and enter data table files and corresponding Array tags.

Then in your MicroLogix, you can address a MSG instruction to the CompactLogix as though the CompactLogix contains those data table files.

There are some RA Knowledgebase documents that include example projects as well. Generally the hardest part is setting up the "Multi-Hop" and routing table settings in the MicroLogix MSG instruction, which is in the ordinary Help and instruction set references for the MicroLogix controller.

 

[Geospark]

This one is quite useful...

32926 - MicroLogix 1100 and 1400 Controllers MSG over Ethernet
Access Level: TechConnect

Note the reference to the MicroLogix 1100 Series A and B differences for the RI file. Also, the Multihop difference when MSG'ing to newer CompactLogix controllers, such as the 1769-L16ER, where the target is the embedded Ethernet port (single hop).

There is also a link in there to explain the PLC/SLC Mapping in the Logix controllers.

Regards,
George

 

[SpecialK87]

Thanks Ken!

I just had a thought. Can I just write from the Compact to the Micro with a "SLC Typed Write"??

 

[SpecialK87]

Thank you George. That's actually exactly what I was looking for. Apparently my "search" skills are not up to par.

 

[Ken Roach]

Yes, it's typically easier to originate the messages in the CompactLogix because it understands the SLC/MicroLogix target addresses without the use of any mapping feature.

When you use an SLC or PLC-5 Typed Read or Typed Write, you can use those controllers syntax as the SLC/PLC side address.

 

[daba]

Yes, it's typically easier to originate the messages in the CompactLogix because it understands the SLC/MicroLogix target addresses without the use of any mapping feature.

When you use an SLC or PLC-5 Typed Read or Typed Write, you can use those controllers syntax as the SLC/PLC side address.

The only caveat for "writing" data to another controller is that you cannot "see" from where the data originates. In a large system with many controllers there is always the possibility for data to be sent to the wrong controller by a badly configured MSG instruction, then it becomes a real PITA to find the culprit.


At least with "read" messages you can immediately determine where the data is coming from.

 

[Geospark]

I do agree that transparency is important in determining the source of local data manipulation. A method I like to use in RSLogix 500 projects, where the source is a write from a Logix 5000 controller, is to assign several words in a dedicated Data File for the Source node. The name of the Data File reflects, as best possible with so few characters, the type of message and the node number. Also, the descriptions for each word in the Data File would reflect the write command from the source, and then the individual bits, if boolean data, will have a "header" in their descriptions denoting that they are externally written to.

Example: (if all boolean data)
Data File: N100 "ND20WRT" (Write From Node 20) with 10 elements N100:0 - N100:9.

Each word description: "MESSAGE WRITE FROM NODE 20"

Bit description: N100:0/0 "Node 20 WRT::Start Command"

Or N100 could have say 100 elements with groups of words for writes from several nodes and be named generally as "WRT_IN", or similar. Each group of words again reflecting the node writing to them in their descriptions.

It does help a lot, especially in busier systems.

I do agree also that it could be possible to incorrectly assign the wrong word(s) addressing in the MSG instruction of a Write controller, especially when a single Data File is used in the target, like in my example with 100 elements. I have had one or two cases before where data was overlapping (two controllers writing to the same block of words). They weren't my projects originally though and the naming convention did nothing to help. In one case a controller was accidentally writing 40 words instead of 20, overlapping the next 20 words being written to by another node. It does take some time tracing the other nodes to find the culprit. But if the target addressing is descriptive enough to identify the correct source, then it at least points you away from that node and on to the others, however many there may be.

Regards,
George