Bug: error when trying to write multiple registers - host.write_multiple_registers()

[beyonlo]

This bug was extracted from PR #10 report, in this reply:

Error when trying to write multiple registers (host.write_multiple_registers())

>>> host.write_single_register(slave_addr=10, register_address=93, register_value=44, signed=False)
True
>>> host.read_holding_registers(slave_addr=10, starting_addr=93, register_qty=1, signed=False)
(44,)
>>> 
>>> host.write_multiple_registers(slave_addr=10, starting_address=93, register_values=[2, -4, 6, -256, 1024], signed=True)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "umodbus/serial.py", line 291, in write_multiple_registers
  File "umodbus/serial.py", line 173, in _send_receive
  File "umodbus/serial.py", line 190, in _validate_resp_hdr
ValueError: slave returned exception code: 1
>>> 
>>> host.write_multiple_registers(slave_addr=10, starting_address=93, register_values=[2, 1024], signed=False)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "umodbus/serial.py", line 291, in write_multiple_registers
  File "umodbus/serial.py", line 173, in _send_receive
  File "umodbus/serial.py", line 190, in _validate_resp_hdr
ValueError: slave returned exception code: 1
>>> 

[brainelectronics]

See Modbus Application Protocol section 6.12

[brainelectronics]

might be connected with this line

micropython-modbus/umodbus/tcp.py

Line 171 in eee18c2

val = request.data_as_registers(signed=False)[0]

due to

• always using signed=False
• always using only first element of unpacked data