v1.2112 & Modbus 1.3 observation

[CNC22369]

I've been testing the latest release with my modbus VFD control macro. Testing with no changes to the modbus function settings (or my macro) has been good -- no errors have been seen so far, but I do see a small hang in looping (maybe a second or less) by observing the function looping debug view. But no errors have been reported, no functions turned red while looping, and the macro functionality worked correctly.

I then changed several write single register functions to one write multiple registers function. The loop started OK (all green) and the data was correct. But, after 30 sec to a minute, the VFD tripped with a communication error. I then ran many times with the same function loop and observed that the loop would hang for 4-10 seconds 2-3 times every few minutes. The VFD tripped with a communication error most of the time. Sometimes the whole loop view would turn red briefly and then return to green looping until the next hang occurred. I disabled the write multiple registers function and went back to the multiple write single register functions. Everything was solid again although I continued to see a small hang (< 1sec) from time-to-time. I went back and forth several times with the same results. I also changed to a different set of registers --- same results.

I'm planning to do additional testing as time permits, but I will probably focus on long-term testing of the modbus setup without the write multiple registers function. I want to make sure the VFD doesn't trip even though the small hangs are happening.

Win 10 (latest)
Hitachi WJ200 VFD
USB generic RS485 comm adapter running at 19.2
Comm line: ~ 1.5m shielded; 200 ohm termination resistors

On a related note the following enhancements to the modbus master may make some things easier to debug.
1. Add a checkbox to allow for stopping looping when an error occurs (so that the error info is still on the screen). Many times the errors flash very briefly during the looping process so that it's virtually impossible to gather any of the error info.
2. Add a single loop execution (step) mode for debug. This could be helpful when setting up/testing functions as any errors should be available on screen. This could be tied to #1.
3. To make data integrity testing easier, implement a function 08h basic loopback test capability.

Thanks, Frank

[dezsoe]

Hello Frank,

Please, upload your profile which has the issues and I'll check the functions.

[CNC22369]

Dezsoe, thank you for taking time to examine by modbus functions. My profile is attached. I ran a few more tests today --- the results are the same. That is, when using the write multiple regs function, from time-to-time there is a noticeable hang in the function looping. This will cause my WJ200 VFD to trip with a modbus comm error (I'm guessing that if the hang occurs when the vfd is trying to communicate, then a trip occurs). When the hang occurs, the functions turn red briefly and then resume green looping until the next hang.

Test setup. I've tried writing to several reg pairs, but for this test I used the WJ200's acceleration parameter r/w reg pair. I set up the data so that both regs received identifiable data. A read function then read the regs to make sure they were written to correctly. This setup fails with the hang issue maybe once a minute. Please note that noticeable hangs (usually short ones) do occur without tripping the vfd. A long hang almost always causes a trip.

WJ200 comm watch-dog timer is set to 5 secs. Its delay before sending a reply is set to 1 ms.

I looped on the same function list but with the write multiple regs function disabled for 30+ minutes with no failures. It seems to be solid, so I'm good-to-go using this list.

I hope this helps to explore this issue.

Thanks, Frank

[dezsoe]

Thanks, I'll check it.