Hi all!
I'm writing a Modbus TCP client using pymodbus3 library.
When asking for some parameters, the response is always a list of int16.
In order to make the values usable, I need to transfer them into 32bit bites,
than put them in the correct order (big\little endian wise), and then to cast
them back to the desired format (usually int32 or float)
I've solved it with a pretty naïve code, but I'm guessing there must be a more
elegant and fast way to solve it with NumPy.
Your help would be very much appreciated!
Nissim.
My code:
def Read(StartAddress, NumOfRegisters, FunctionCode,ParameterType,BitOrder):
# select the Parameters format
PrmFormat = 'f' # default is float
if ParameterType == 'int':
PrmFormat = 'i'
# select the endian state - maybe move to the connect function?
endian = '<I' # default is big endian
if BitOrder == 'little':
endian = '>I'
# start asking for the payload
payload = None
while payload == None:
payload = Modbus.read_input_registers(StartAddress,
NumOfRegisters)
#### parse the answer
ResultRegisters = []
# convert the returned registers from list of int16 to list of
32 bits bitmaks
for reg in range(int(NumOfRegisters / 2)):
ResultRegisters[reg] = struct.pack(endian,
payload.registers[2 * reg]) + struct.pack(endian,payload.registers[2 * reg + 1])
# convert this list to a list with the real parameter format
for reg in range(len(ResultRegisters)):
ResultRegisters[reg]=
struct.unpack(PrmFormat,ResultRegisters(reg))
# return results
return ResultRegisters
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