Modbus TCP connection datakom d-200 mk2

[admin]

There's no "read single register" function in modbus, this only applies to writing where there are two different commands for single/multiple registers.
Keep in mind that voltage registers are 32-bit so each value consists of 2 registers. This might be why profile was not working for you.
Another thing is that you should not close the connection after each run. Profiles also support this by enabling "persistent" connection mode.

See if this works for you:

Code:

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if not mb then   require('luamodbus')   mb = luamodbus.tcp()   mb:open('10.36.0.25', 502)   mb:setresponsetimeout(5)   res, err = mb:connect()   if not res then     log('modbus connect failed ' .. tostring(err))     mb:close()     mb = nil   end end if mb then   reg10240, reg10241, reg10242, reg10243, reg10244, reg10245, reg10246, reg10247 = mb:readregisters(10240, 8)      if reg10240 then     mains_l1_voltage = reg10240 * 0x10000 + reg10241     mains_l2_voltage = reg10242 * 0x10000 + reg10243     mains_l3_voltage = reg10244 * 0x10000 + reg10245     genset_l1_voltage = reg10246 * 0x10000 + reg10247     log('voltage values', mains_l1_voltage, mains_l2_voltage, mains_l3_voltage, genset_l1_voltage)   else     log('modbus read failed ' .. tostring(reg10241))     mb:close()     mb = nil   end end