GraemeTownsend
Member
Hi All.
I have a project running 3 x MODBUS channels out of a SM2 module configured as a RTU Master. There are two MODBUS slaves on each channel, (simple 3rd party I/O devices, they just sit as slaves taking instructions).
I have built a very simple logic process, basically a repeating timer that cycles through the reads and writes. (I know it is not the best).
However, I am starting to see a few issues.
1/ It would appear to me that the three SM2 channels are not independent, i.e. a comms error on one impacts the other two channels. (If this is indeed true, I have no idea why AB bothered building a three channel device!).
2/ What's the best way to logic flow this? I'm about to go down the path of waiting for the DN (or ER) bit before continuing rather than timer based. But I'm still concerned about errors impacting the other channels....
Any advice greatly welcomed.
Cheers,
Graeme.
I have a project running 3 x MODBUS channels out of a SM2 module configured as a RTU Master. There are two MODBUS slaves on each channel, (simple 3rd party I/O devices, they just sit as slaves taking instructions).
I have built a very simple logic process, basically a repeating timer that cycles through the reads and writes. (I know it is not the best).
However, I am starting to see a few issues.
1/ It would appear to me that the three SM2 channels are not independent, i.e. a comms error on one impacts the other two channels. (If this is indeed true, I have no idea why AB bothered building a three channel device!).
2/ What's the best way to logic flow this? I'm about to go down the path of waiting for the DN (or ER) bit before continuing rather than timer based. But I'm still concerned about errors impacting the other channels....
Any advice greatly welcomed.
Cheers,
Graeme.
