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emelianov / modbus-esp8266

Most complete Modbus library for Arduino. A library that allows your Arduino board to communicate via Modbus protocol, acting as a master, slave or both. Supports network transport (Modbus TCP) and Serial line/RS-485 (Modbus RTU). Supports Modbus TCP Security for ESP8266/ESP32.

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pullHreg - how to modify local registers

chrgraf opened this issue · comments

commented

Dear Alexander,

first thanks for this cool lib.

From reading the doc, I am having issues to understand the pullHreg method:
uint16_t pullHreg(IPAddress ip, uint16_t from, uint16_t to, uint16_t numregs = 1,..

  1. meaning of from/to: do those values denote the starting and the ending-range when reading registers? e.g .would mb_real_meter.pullHreg(real_meter_ID, 243, 299); read all Holding registers from starting-range 243 upto 299 (so in total 46 regs)?
  2. the docs state: Result is saved to local registers. Method returns corresponding transaction id. [ip/from] or [ip/offset] - slave, [to] or [startreg] - local
    Kindly asking how to access and modify those registers please

thanks

christian

commented

Regarding number two - I got this to work in my code. Basically, you have to establish a local register on the master device with the modbusObject.addHreg(local_hreg_address) function. Then you pull the result from the remote (slave or server) register, to your local register. So pullHreg(slave_address, slave_hreg_address, local_hreg_address). Then you can read the local hreg via the .Hreg() function: modbusObject.Hreg(local_hreg).

Someone else feel free to correct me if I'm doing this wrong.

commented

thanks alot!