Damian Posted August 27, 2010 Report Share Posted August 27, 2010 So ................ Having been unable to get any reliability using DF1 communication between the L35E and the V570, I decided to try and see if using modbus RTU between the two would get better results. For some reason, the V570 doesn't seem to be responding to the Modbus commands. I have the L35E acting as a master using the standard Uni programming cable between it and Comm 1. Using "Info Mode" I can see that all the parameters are set OK and that Com1 is set for Modbus. When looking at the receive buffer in Hex mode I even see the Mobus messages coming in perfectly. Everything seems to be framed and formatted properly. So I know that the data is getting to the V570 fine. It just refuses to respond to it. I hooked my PC up directly to the output of the L35E and monitored the port with a modbus sniffer. The software had no issues picking up the communications. Attached are some screen shots of the setup. Any thoughts would be greatly appreciated. D Quote Link to comment Share on other sites More sharing options...
MVP 2023 Joe Tauser Posted August 27, 2010 MVP 2023 Report Share Posted August 27, 2010 The V570 is not listening for Modbus commands. The Modbus Scan_EX needs to be solved all the time, not just on the first scan. Put it in the following network behind a NC of SB 2. Joe T. Quote Link to comment Share on other sites More sharing options...
Emil Posted August 28, 2010 Report Share Posted August 28, 2010 Small note: At Unitronics site www.unitronics.com > Support page > PLC tools and applications you can find detailed doc on how to perform communication via DF1. In VisiLogic > Help menu Examples there are few working demoes, related to Modbus. I'll recommend to take a pair of such examples - Master and Slave, connect two controllers and chech the data flow. Then, replacing one of the contrololers with your device, check again port settings and try again. Quote Link to comment Share on other sites More sharing options...
Damian Posted August 29, 2010 Author Report Share Posted August 29, 2010 The V570 is not listening for Modbus commands. The Modbus Scan_EX needs to be solved all the time, not just on the first scan. Put it in the following network behind a NC of SB 2. Joe T. Hi Joe, You raise a good point. I did originally have the SCANX on its own network with no conditions in front of it, but it wasn't behaving any differently though. But now I can't remember if there were other problems previous to that I may have latter corrected. I'll give it a try in the morning and see how it goes. Thanks for pointing out the dumb mistake. I'm going to be very angry with myself if that was all the problem was. D Quote Link to comment Share on other sites More sharing options...
Damian Posted August 29, 2010 Author Report Share Posted August 29, 2010 Small note: At Unitronics site www.unitronics.com > Support page > PLC tools and applications you can find detailed doc on how to perform communication via DF1. In VisiLogic > Help menu Examples there are few working demoes, related to Modbus. I'll recommend to take a pair of such examples - Master and Slave, connect two controllers and chech the data flow. Then, replacing one of the contrololers with your device, check again port settings and try again. Hi Emil, Thanks for the note, but you may not have noticed my post a while back regarding having issues with the reliability of the DF1 communication. It should also be noted that there are some errors in the document you mention (and in the help files) that should be corrected. I've done quite a bit with mobus RTU on the V570/V280 with success so this is nothing new to me. If fixing the programming error that Joe pointed out does not fix the problem I will send the application into you guys to have a gander. Thanks, D Quote Link to comment Share on other sites More sharing options...
Emil Posted August 30, 2010 Report Share Posted August 30, 2010 Hi Damian, About DF1. This is not our protocol and we have no too much experience with it. The doc I pointed was writen and given to us by our distributor in Finland, which is distributor of AB too. I know that this doc helped a lot of people. We will appreciate very much any note, wich points to errors and will help to improve this doc. I hope you will send your remarks to me ASAP! About Modbus - did you try my advice to take a pair of working examples and check with them? What is the result? Of course you're welcome to send your application and we will check it here - but with another Vision as master or simulating program. We have no L35E to check with it and if te problem is there or in communication parameters, this will not fix the problem. Quote Link to comment Share on other sites More sharing options...
Damian Posted August 31, 2010 Author Report Share Posted August 31, 2010 The V570 is not listening for Modbus commands. The Modbus Scan_EX needs to be solved all the time, not just on the first scan. Put it in the following network behind a NC of SB 2. Joe T. Joe, It's official. That was crux of the problem. At least in the end. In the beginning I had the ladder correct but must have had something else messed up. By the time I had fixed the real issue I must have already screwed the ladder up. It's time to go soak my head in a bucket of water. Many thanks! D Quote Link to comment Share on other sites More sharing options...
Damian Posted August 31, 2010 Author Report Share Posted August 31, 2010 Hi Damian, About DF1. This is not our protocol and we have no too much experience with it. The doc I pointed was writen and given to us by our distributor in Finland, which is distributor of AB too. I know that this doc helped a lot of people. We will appreciate very much any note, wich points to errors and will help to improve this doc. I hope you will send your remarks to me ASAP! About Modbus - did you try my advice to take a pair of working examples and check with them? What is the result? Of course you're welcome to send your application and we will check it here - but with another Vision as master or simulating program. We have no L35E to check with it and if te problem is there or in communication parameters, this will not fix the problem. Hi Emil, The DF1 document is actually quite helpful. There were some explanations, corrections, and clarifications that found their way on the old Forum which would be of great benefit to be merged into the document. There are also some translation issues that make it a difficult read in some spots, but it is definitely valuable. If they are OK with it, I am willing to edit their version of it to get it more up to date. My Modbus issue is solved (for the most part). JT hit the nail on the head. As I mentioned before, I've had Uni's talking modbus to eachother before, to mocking that up again wasn't going to do me a whole lot of good. Somthing now obvious is that there is an issue with the reliability of the DF1 communication between the AB and the Uni. When I have the two talking DF1 I get very frequent comm errors and prolonged timeouts before communications kick back in. Changing absolutely no hardware (Exact same cable between the exact same ports) and using ModbusRTU instead, I have run for several hours now without one single comm error or timeout. This is all with the same comm settings as well (38400,8,N,1). The only change made was protocol. I wish I had more time to figure out where the problem is, but now that I have the communications working in Modbus I can't afford to spend too much time with the DF1 at the moment. Perhaps when the job is finished. Thanks for your help, D Quote Link to comment Share on other sites More sharing options...
Emil Posted August 31, 2010 Report Share Posted August 31, 2010 Hi Damian, First of all - I'll be more than thankfull if you will take your time and will edit DF1 help doc. We will post your edition right in this forum (there was no such opiton in prevous forum, but now it is!). I guess a lot of people all around te world will be thankfull to you too! About unstability of DF1 - I'll see how we can check it... Quote Link to comment Share on other sites More sharing options...
Damian Posted June 11, 2012 Author Report Share Posted June 11, 2012 To close the loop on this .................. If you end up in this thread and wonder what ended up being the DF1 stability issue I was having, please search for "Trouble with SLC communication" in this forum. There was a bug with the DF1 comms that was discovered and fixed. Quote Link to comment Share on other sites More sharing options...
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