Micrologix 1400 data queue read?

Hi,

I have recently started to work with ML1400 already configured in our company environment. I use KEPserverex as an OPC server to get useful data from the PLCs.

I was able to read discrete values like F8:0 etc which is great, but it would be even better if I would be able to read the data queues since those are the most relevant data for us (storing measurement data)

Is it possible to do it via the KEPserverex? If not how can I do that? We have the Micrologix data extract utility but it is really slow and I'd like to query and process the data in the LabVIEW programming tool, so the solution should work there. (even OPC or maybe activeX would be fine). Based on the economics it supposed to be free

Please let me know,
thx,
i-

What are you calling data queues?

Ken Moore said:

What are you calling data queues?

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As far as I am concerned the data queues are some sort of memory banks where our PLCs store measurement data about our processes. What I know about them: we have 6 queues, queue0 stores the most relevant data. I was told only 5000 records can be stored in this queue and if we dont read them they will be overwritten by the new data. Thats why we use the ML data extract tool, but thats slow as hell. This tool creates folders on our HDD with the following folder name: AB_ETHIP-1 192.168.0.11 Queue 0

I hope this clarified a bit what I try to talking about. (I am really new in the PLC scene, so maybe my terms are not that accurate)

What are you calling data queues?

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I believe the OP is talking about the "DLG" Data Log Instruction.

See PDF below about retrieving the log info. Note, I have never try this.

Mickey said:

I believe the OP is talking about the "DLG" Data Log Instruction.

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Yes, actually this is what I'd like to query. I am wondering if there is a simple way to read the DLG queues.

sorry for reviving a old thread, but I'm wondering if you ever found a "clean" solution for reading a DLG file?

gmaendel said:

sorry for reviving a old thread, but I'm wondering if you ever found a "clean" solution for reading a DLG file?

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Nope...

Not sure if anyone is still looking for info on this.

I developed a python method, after a bunch of searching, using the pycomm3 library. I was using a ML1400 PLC so I modified the slc.driver.py file in my own fork to add some data logging reading functionality.

my fork can be downloaded here:
https://github.com/ddeckerCPF/pycomm3

Essentially the data log function requires the queue number and the number of items to be read. The function also expects that you are reading the whole queue and not a partial queue. There is a line of code that does an extra read after the whole queue is read since the DataLog memory has an issue where it keeps the last log in after the whole queue is read.

I attached a sample python code for reading a data log queue over ethernet with a micrologix 1400 PLC.