Manual optoNCDT 1402 - Micro-Epsilon

Serial Interface RS422Since most serial interfaces use an 8 bit data format, 4 consecutive bytes are combined into a 32 bit word.Each command packet has a header consisting of two 32 bit words followed by the command and, if required,other data as well. The top two bits (No. 31 and 30) are always “0“ in the transmitted command.8.4.2 Communication without ErrorNo start word is transmitted if the sensor replies to a command. The 1st word is then the sensor identifier. Thesecond word is the command with set MSB (Bit 31 = 1, corresponding an OR operation of the command with0x8000) and the new package length if there was no error during communication. With longer answers (e.g.GET_INFO) the package length is larger according to the quantity of data words to be transmitted. A firm32 bit word 0x20200D0A forms the conclusion of the answer. The conclusion word is not a data word.8.4.3 Communication with ErrorIf the sensor detects an error during the execution of a command, the second highest bit (bit 30) of the commandis also set (the command is OR operated with 0xC000). Additionally a command error code is transferredas data word, see Fig. 26. The resulting package length now amounts to 3 data words. The reply isfinished with a 32 bit word 0x20200D0A (2 blank charecters + CR + LF).Error Code X Description1 Command unknown2 Incorrect parameter value3 Invalid parameter4 Time out5 Command failed6 Warning for averaging type and averaging number 1Fig. 26 Command error codes1), see Chap. 8.4.7optoNCDT 1402Page 51