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<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed">Hi all!<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed">I'm writing a Modbus TCP client using
<b>pymodbus3</b> library.<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed">When asking for some parameters, the response is always a list of int16.<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed">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)<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed">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.<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed">Your help would be very much appreciated!<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed">Nissim.<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed"><o:p> </o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed">My code:<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed">def Read(StartAddress, NumOfRegisters, FunctionCode,ParameterType,BitOrder):<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed"> # select the Parameters format<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed"> PrmFormat = 'f' # default is float<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed"> if ParameterType == 'int':<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed"> PrmFormat = 'i'<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed"> # select the endian state - maybe move to the connect function?<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed"> endian = '<I' # default is big endian<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed"> if BitOrder == 'little':<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed"> endian = '>I'<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed"> # start asking for the payload<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed"> payload = None<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed"> while payload == None:<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed"> payload = Modbus.read_input_registers(StartAddress, NumOfRegisters)<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed"> #### parse the answer<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed"> ResultRegisters = []<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed"> # convert the returned registers from list of int16 to list of 32 bits bitmaks<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed"> for reg in range(int(NumOfRegisters / 2)):<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed"> ResultRegisters[reg] = struct.pack(endian, payload.registers[2 * reg]) + struct.pack(endian,payload.registers[2 * reg + 1])<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed"> # convert this list to a list with the real parameter format<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed"> for reg in range(len(ResultRegisters)):<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed"> ResultRegisters[reg]= struct.unpack(PrmFormat,ResultRegisters(reg))<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed"> # return results<o:p></o:p></p>
<p class="MsoNormal" style="text-align:left;direction:ltr;unicode-bidi:embed"> return ResultRegisters<o:p></o:p></p>
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