COP in SLC5/05

[EMHBH 0]

Hi, Trying to read a LAD file made for SLC5/05, I’ve noticed that Source is #M1:1.3400 ( as shown in the attached screen shot ), my questions are: - There is no file start with M in the Data Files. - The last number in the Source file (.3400) is what? Thanks

[b_carlton 61]

The 'M' files represent information, beyond the standard Input or Output words, which resides in specialized I/O modules. It must be transferred, to or from the module, using these instructions. The information does not automatically show up in a data table. This particular address represents input data (the first '1') from the module in slot 1 (the second '1'). I would bet that this is a Remote I/O interface module given the value of '3400'. This particular instruction is copying two words of information. Edited 9 Aug 2015 by b_carlton

[EMHBH 0]

You are right, this is coming from the 1747-BSN backup scanner module for Remote IOs.

[nehpets 19]

I would appear that the COP instruction is copying the system status word (3400) and the module status word (3401) of the backup scanner in slot 1 into binary file B3:1 and B3:2 respectivley. Steve

[EMHBH 0]

Hi again, Attached is a screen shot of page 6-97 from Rockwell Automation booklet about Backup Scanner Module ( 1747-BSN ). The publication number is 1774-6.22 Thanks

[b_carlton 61]

Just a little more information on accessing the information in M files using this COPY technique. A contact in ladder logic can have a reference such as M1:1.3400/6 and run correctly. But, each time an 'M' reference is encountered the system must switch to an I/O read to get (or send) the information to/from the module. This is a MUCH sower process than reading data in memory. - An example from the manual for a SLC 5/03 - an XIC command from an internal bit took .44 microseconds. An XIC from an 'M' address took 782 microseconds. Therefore it is advised to use this COPY technique both for reading and writing information to/from the module and that it be done at most once per scan. In your above example the system can read the status of a bit in the 'B' registers much faster than it can read a bit from the module's 'M' registers. Edited 12 Aug 2015 by b_carlton