# Modbus Connection Issue **URL:** \ **Category:** Ignition\ **Created:** [October 19, 2011, 2:18pm UTC](https://forum.inductiveautomation.com/t/modbus-connection-issue/3459 "2011-10-19T14:18:21Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![jgreenewv](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@jgreenewv](https://forum.inductiveautomation.com/u/jgreenewv)\ **Post date:** [October 19, 2011, 2:18pm UTC](https://forum.inductiveautomation.com/t/modbus-connection-issue/3459/1 "2011-10-19T14:18:21Z")
I’ve run into an odd one here. I have a project I’m migrating from FPMI/FSQL. The old system was using Kepserver, but I’m switching it over to the Ignition Modbus driver. The controller is a Horner Electric QX451. If I set the project up using the Modbus v1 driver, it connects, I can pull data, and everything is fine. If I set the project up using the Modbus v2 driver (which is what’s licensed currently) it will connect, but then drop out after a few seconds, and I can’t pull any data. Anyone seen behavior like this before? Are there any solutions other than get the license modified to add the v1 driver and use that? Thanks! Joe ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [October 19, 2011, 2:31pm UTC](https://forum.inductiveautomation.com/t/modbus-connection-issue/3459/2 "2011-10-19T14:31:49Z")
Can you send in your log files, or better yet, call support and let them poke around? There shouldn’t be any reason v1 would work and v2 wouldn’t. ---
**Author:** ![jgreenewv](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@jgreenewv](https://forum.inductiveautomation.com/u/jgreenewv)\ **Post date:** [October 19, 2011, 4:14pm UTC](https://forum.inductiveautomation.com/t/modbus-connection-issue/3459/3 "2011-10-19T16:14:39Z")
OK, never mind. I walked away for a while to work on something else, came back, re-created the device, and it’s working now. My assumption is that is was too early on a rainy morning, and I lost the ability to spell correctly or something. 😊 ---
**Author:** ![DennisWomack](https://avatars.discourse-cdn.com/v4/letter/d/51bf81/32.png) [@DennisWomack](https://forum.inductiveautomation.com/u/DennisWomack)\ **Post date:** [November 9, 2011, 3:42pm UTC](https://forum.inductiveautomation.com/t/modbus-connection-issue/3459/4 "2011-11-09T15:42:34Z")
Several questions: Should a Modbus v1 coniguration and addressing work with a Modbus v2 driver? Can both drivers coexist in the same gateway talking to the same PLC? Should exporting the addressing from v1 and importing in v2 result in a working system? Thanks for the help. Dennis ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [November 9, 2011, 3:46pm UTC](https://forum.inductiveautomation.com/t/modbus-connection-issue/3459/5 "2011-11-09T15:46:46Z")
> Should a Modbus v1 coniguration and addressing work with a Modbus v2 driver? Yep! > Can both drivers coexist in the same gateway talking to the same PLC? Yep! But as of 7.3 you can't add new Modbus v1 devices. > Should exporting the addressing from v1 and importing in v2 result in a working system? The addressing is exactly the same. The only thing to watch out for is poorly named prefixes, i.e., any prefix that could also be interpreted as an address. This makes things like HR\*, IR\*, C\*, and DI\* poor choices for prefixes. ---
**Author:** ![DennisWomack](https://avatars.discourse-cdn.com/v4/letter/d/51bf81/32.png) [@DennisWomack](https://forum.inductiveautomation.com/u/DennisWomack)\ **Post date:** [November 10, 2011, 11:09pm UTC](https://forum.inductiveautomation.com/t/modbus-connection-issue/3459/6 "2011-11-10T23:09:32Z")
I currently have a Panel Edition that was at 7.2.9. It had Modbus v1 with one device defined with some address ranges defined. I got the CD Key upgraded to 7.3. Since it had Modbus v1, that is now running in demo mode. It still works but times out. I exported the addresses and imported them into a modbus v2 instance of another device. This device was given the same ip address as the modbus v1 device. I tried disabling one and enabling the other, while swapping the names of the devices. So only one modbus device is active at once. This procedure did not produce identical results. I don’t understand why. Help! Dennis ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [November 10, 2011, 11:23pm UTC](https://forum.inductiveautomation.com/t/modbus-connection-issue/3459/7 "2011-11-10T23:23:18Z")
Can you call support and have them take a look? ---
**Author:** ![DennisWomack](https://avatars.discourse-cdn.com/v4/letter/d/51bf81/32.png) [@DennisWomack](https://forum.inductiveautomation.com/u/DennisWomack)\ **Post date:** [November 22, 2011, 10:03pm UTC](https://forum.inductiveautomation.com/t/modbus-connection-issue/3459/8 "2011-11-22T22:03:48Z")
Kevin, I finally got around to looking at the installation again. I have one Modbus v1 running talking to the machine. I have one Modbus v2 running talking to the same machine. I got it to work. I had to check check the swap words box in the Modbus v2. The Modbus v1 instance does not have it checked. Does that sound right to you? Doesn’t to me. Thanks, Dennis ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [November 22, 2011, 10:05pm UTC](https://forum.inductiveautomation.com/t/modbus-connection-issue/3459/9 "2011-11-22T22:05:35Z")
Doesn’t sound right to me either. They should behave the same…