Artisan supports all variants of the MODBUS protocol.

  • MODBUS Serial ASCII
  • MODBUS Serial Binary
  • MODBUS Serial RTU
  • MODBUS TCP
  • MODBUS UDP

It can be configured to read registers via functions 1, 2, 3 and 4 for up to 8 data channels. See the posts Modbus RTU and More Modbus for configuration details.

Integer divisions by 10 and 100 are supported. Bytes and words are can be big or little endian ordered. Data can be interpreted as Temperature (C/F) or just numbers. Finally the following decoders are available to convert the received bytes into numbers.

Decoder Bits Registers Description Old name
uInt16 16 1 unsigned Integer Int
uInt32 32 2 unsigned Integer Int32
sInt16 16 1 signed Integer –
sInt32 32 2 signed Integer –
BCD16 16 1 unsigned Integer, BCD decoded BCD
BCD32  32  2 unsigned Integer, BCD decoded BCD32
Float32 32  2 Float Float

PID mechanism of external devices can be connected via MODBUS to the Artisan PID controls (see the post on PID support for details).

Buttons and sliders can send out MODBUS Commands via MODBUS functions 5, 6, 15, 16 and 22. The following commands in the action description are supported.

Note that MODBUS Command actions can be sequenced by separating them with semicolons like in read(0,10); mwrite(0,20,255,0,_)

  • read(slaveId,register):
    reads from slave using function 3 (Read Multiple Holding Registers). The result is bound to the placeholder `_` and thus can be used in later commands.
  • writeSingle([slaveId,register,value],..,[slaveId,register,value]):
    write single register via function 6 (int)
  • writeWord([slaveId,register,value],..,[slaveId,register,value]):
    write register via function 16 (float)
  • write([slaveId,register,value],..,[slaveId,register,value]):
    write register via function 6 (int) or function 16 (float)
  • wcoil(slaveId,register,<bool>):
    write coil via function 5
  • wcoils(slaveId,register,[<bool>,..,<bool>]):
    write coils via function 15
  • mwrite(slaveId,register,andMask,orMask):
    mask write register via function 22
  • mwrite(slaveId,register,andMask,orMask,value):
    fake mask write register which evaluates these masks on the value and writes the result using function 6. Together with a previous read to set the temporary variable _ this can be used to simulate a mask write register (function 22) if the PLC does not support it directly.
  • writem(slaveId,register,value) and
    writem(slaveId,register,[<int>,..,<int>]):
    write multiple holding registers via function 16
  • writeBCD([s,r,v],..,[s,r,v]):
    write multiple holding registers BCD encoded via function 16
  • sleep(s) :
    delay processing by s seconds (float)
  • button(<b>) :
    sets the last button pressed to either “pressed” if b is 1 or True, and “normal”, otherwise

The placeholders {BT}, {ET}, {time} substituted in MODBUS Command actions by the current bean temperature (BT), environmental temperature (ET) or the time in seconds (float).

Updated: