Mettler Toledo IND 570 to 317-2 PN/DP

[MHennel]

I am working on an older system where they are switching out the weigh in motion scale on a conveyor system from an AP Dataweigh to a Mettler IND570. The communications is over Profibus DP. On the old scale and many previous versions of Mettler scales over the years I have never had an issue. I just want the final weight at the end of the weigh cycle. Nothing else and I don't need to send any commands to the scale. Previously the final weight was sent to a input word and it would need to be ack'd by setting a bit or two in the output word. Then the cycle repeats. On this particular scale the only weight I ever see in the input table is the instantanious weight on the scale, never a final weight. All other input areas are empty except for the status word. I do see some status change as boxes go over the scale. Has anyone seen something like this before? In the documentation I have and the sample program from Mettler provides these results. I have not been able to make any PLC changes that make any difference. The techs onsite have never installed a Profibus card on a scale before and can't see anything in the scale to change. I can hook a terminal emulator to the serial port and get the data exactly as required, but I need it over Profibus. Any suggestions?

 

[Frost999]

I am moving from 560s to 570s currently... I haven't had time to examine the scale-side programming yet. I am in about the same boat, however, I have some extra I/O around and that gives me the trigger I need to snap-shot the instantaneous weight at the right time.

They have a "programming group" of guys down in NC that usually are involved with sales to get the specifics right before they ever get installed. Have you talked to those guys? They have helped me out (up front of purchase) on my particulars.

 

[MHennel]

I can get the instaneous weight at the end of the scale since the exit PE is part of the status word. The problem is that the instaneous weight at that point is not necessarily the measured weight value. It can be off by a fairly significant value. I was able to get some information from a collegue that I think will get me out of my issue. I need to issue a read command when the exit PE is triggered and I should get the measured weight. Then you need so send some addititional commands to restart the cycle. I should be able to test later this week.

 

[MHennel]

I have it working now. What used to be quite simple to receive scale weight is now very complicated. You have to send a request to the scale to get the data and you have to send the correct Shared Data Command to get the weight value you want. Then a bunch of Ack's resets to repeat the cycle. It works, but is a lot more effort than it should be to just get the processed weight at the end of weigh cycle.