Modbus 8bit low and high

[Daniel]

Try this, you may need to subtract -1 from the register.

Code:

if not mb then
require('luamodbus')
mb = luamodbus.rtu()
mb:open('/dev/RS485', 9600, 'E', 8, 1, 'H')
mb:connect()
end


mb:setslave(1)

value = mb:readregisters(21)
address = bit.rshift(value, 8)
baudrate = value-address*256

log(address,baudrate)

newaddress = 2
newbaudrate = 1
reg=newaddress*256 + newbaudrate

mb:writeregisters(21, reg)