M0 and M1

  • Thread starter joe de montreal
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joe de montreal

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Hi all, I'm buiding a program with rslogix500, 5/04 to control 30 convoyor with devicenet drive. Bultin 160.

Why, in rslogix500, there is no M0 and M1 files in the database. Or, why 1747-SDN scanner used M0 and M1 file and not support integer file (n7:0) like 1771-SDN??????

Secondly, why i can't viewing M0 and M1 files in the database, but can programed them???

We can put a NC, NO or OTE contact but we cannot seeing the database like counter, integer, binary and other's!!!!

All of my drive works fine, but 1771-SDN are better then 1747-SDN


Bye Bye
 
so you're on this board too?

Here’s some information right out of the book:

M0 and M1 Data Files - Specialty I/O Modules

M0 and M1 files are data files that reside in specialty I/O modules
only. There is no image for these files in the processor memory. The
application of these files depends on the function of the particular
specialty I/O module.
Click to expand...

The book goes on to explain how to access and control the M0 and M1 files. Here is a handy link to the book:

SLC-500 Instruction Set Reference Manual

Start reading on Adobe Reader page 531 of 582 - (yeah, the good stuff is always way in the back) - this is book page E19 -

Take a look at this material and then please post again with any specific questions you might still have.
 
Hi Joe,

When I use the 1747-SDN, I always use COP instructions to move the whole M0 and M1 file to or from an Integer (Nx:yy) file.

It slows down your controller severely to simply address the M-file bits in ladder logic. Every reference adds about 2 milliseconds to your scan time. I simply take that 2-millisecond hit about twice as often as my DeviceNet scantime (for 30 drives, probably in the 30-40 millisecond range) by programming in the COP instructions.

When I'm doing a lot of drives, I also use Segmented Mapping in RSNetworx for DeviceNet to put the start/stop/jog first Word for the drives into the discrete I/O table, and put the second Word (speed reference) into the M-file. It takes a little bit of extra labor on the RSNetworx side, but it makes the system speedier and a easier to program because my drives are more uniformly addressed (instead of having some entirely in I/O and some entirely in M-files).
 
The M-files in the 1747-SN RIO scanner are a little bit different from the ones in the 1747-SDN DeviceNet scanner.

In the RIO scanner, the M-files consist of 32 segments of 100 words each, of which 64/100 are actually used as buffers for RIO block transfers.

In the DeviceNet scanner, the first 150 M-file words are an expanded I/O data table. Status words follow that, as do Explicit Message command buffers that work more like the M-file buffers on the RIO scanner.

The best publication I've found, with the best diagram of 1747-SDN memory, is the Installation Instructions for the module. I have two pages from this taped to the wall of my office next to the Dilbert cartoons.

http://www.ab.com/manuals/io/1747/1747-in058c-en-p.pdf
 
Joe's not even doing anything as complex as block transfers; he's just using the extended I/O table inside the 1747-SDN DeviceNet scanner.

I've pushed the SLC guys for an explicit message instruction in the SLC to take the complexity out of using the messaging capability in the 1747-SDN, but it's not really in the cards. Doing explicit messages in the Logix is like falling of a log by comparison.
 
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