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Everything posted by jacameron2015

  1. Hi Alexander, I tried to upload the program here, but the file size is too large - even when zipped. I initially wrote the logic for this sequence without timers, but then added them in because the routine wasn't working. I've now removed the timers. I found that what was actually causing the routine to get stuck on attempting to connect to an unavailable slave was an always-on contact that kept starting the process again. The sequence started to work when i fixed the issue with that contact. Thanks again for all your help. - James
  2. Hi Alexander, Thanks again for your assistance. Yes, when i looked up the corresponding meanings of Modbus status codes 4 and 5, i saw that it was an issue of not being able to connect to the target slave controller. Further to what you're saying, the Modbus RC operation is successful for the 2 controllers that are actually connected in this test setup. What i need though is for the master controller to keep looping through reading the coils on each of the slave controllers after a say 5-second interval. It's important for the master controller to be able to skip over communicating with an unreachable slave on each iteration and just carry on. Any thoughts on how to achieve this? Many thanks again, James
  3. Hi Alexander, Thanks for the quick response. I'm using a memory bit for the read request to each PLC. I'm using a direct contact of this memory bit in series with the inverted contact of Modbus Function in Progress. I'm setting the MB for the next device to be read and resetting the MB for the device requested for read in the current Ladder rung. The Modbus status code alternates between 4 and 5 for a device that's not connected during the test. This is where Function in Progress also gets stuck on. - James
  4. Hi, I'm writing an application involving 1 master and 9 slave controllers - all Unitronics. The master PLC is a V1210. One of the slaves is also a V1210. The remaining 8 slaves are V130s. All i'm trying to do is sequentially read 1 coil from each of the slave PLCs. I know that this should be ridiculously easy... ...However, I'm finding that the "Function in Progress" bit gets stuck on after the master only attempting to read from 2 of the slaves. I've tried using timers of 100ms - probably excessive - after each Modbus Read Coils function block. Also, just to mention, I don't have all 9 slave controllers with me for testing - I've got 2. Is Modbus good at handling when it can't get thru to a particular node and just moving on to attempt the next one? Any help much appreciated, James
  5. Hi Mike, Thanks for looking at this. I've now emailed the project file to Unitronics Support. - James
  6. Hi, A subroutine in my program uses a few timers. However, when the first timer starts it then stops after only 0.15 seconds have elapsed - the preset value is 10s - and the program flow does not progress beyond that ladder net. Attached is a screenshot showing the relevant part of the ladder during runtime. Sorry if the solution to resolving this is really obvious, but please could someone suggest how to correct this? Many thanks in advance. - James
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