I am trying to use libmodbus3.0 on a TS7390 board to do modbus communications
over a half duplex RS485 port. I'd be using pins 1 & 6 from the COM2 header.
The board is running kernel 2.6.21-ts. From what I understand, I must first
enable the RS485 HD mode before I can use /dev/ttts3 for rs485 modbus
communication.
I attempted to use the ioctl call referenced in the documentation to achieve
this. From what I gather from searching the group posting, that will not work
with kernel 2.6.21. In my case, the ioctl call was always returning -1.
So now it looks like I'll need to write to the registers using mmap. However,
I do not know which address to write to for the TS7390. I've seen posts doing
similar for the TS7260 and TS7800, but nothing for the TS73xx series.
If someone could point me in the write direction as far as which address to
write to, or better yet provide the few lines of sample code that'd set up half
duplex 485 at 9600 baud on /dev/ttts3, it'd be very much appreciated.
Thanks,
Brian Gallaway
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