Default block unit length is two bytes why?

[hxmwr]

modbus-tk/modbus_tk/modbus.py

Line 500 in 14c70f2

response += struct.pack(">"+fmt, reg)

Every block unit length must be 2 bytes, is this part of protocol or just convention for this project. If I have a UINT (4 bytes) value, I have to split it to 2 WORD and then store it in two block units (if not, struct.pack would failed when reading), when reading this value I have concat these two WORD and this is not so convient.

[blotsome]

In Modbus, Holding Registers and Input Registers are 16-bit (2 bytes) per register. This is a protocol convention. It is very common for 32-bit data to be stored in 2 registers, for example floating point or as you mentioned UINT32. There is no standard on which register goes first when decoding, which is why software like modscan32 allows you to select between MSR and LSR. It is a limitation of the protocol, but I guess something you get used to when working with modbus.