NEC PX-42VM3A User Manual

Also see for PlasmaSync 42MP3: User manual

NEC PX-42VM3A User Manual Manual pdf 46 page image

E-40Communication FormatCommand 1Unit ID 1Unit ID 2Command 2Data lengthDataCheck sum8 bit 8 bit 8 bit 8 bit 8 bit 8 bit 8 bit 8 bitCommand 1Command 1, along with command 2, is a number used todistinguish each command.In the case of ACK, when the lower order 4 bits is FH (asin 3FH and 7FH), this indicates that the commands anddata of the supported equipment have been received. Whenthe lower order 4 bits is BH (as in 3BH and 7BH), thisindicates that unsupported commands and data have beenreceived.Unit ID 1 and Unit ID 2Unit ID 1 and unit ID 2 are numbers used to identify theequipment that is to be connected.60H is used for the plasma monitor and 80H is used forexternal control equipment such as a personal computer.1) Unit ID 1: Indicates the equipment sending the signal2) Unit ID 2: Indicates the equipment receiving the signalCommand 2Command 2, along with command 1, is a number used todistinguish each command.Check Sum (CKS), Error Processing, and ACK1) The check sum described below and RS-232C oddparity are used together for a check of the received data.The check sum is the lower order 8 bits of one frame ofsent or received data comprising the sum total ofCommand 1, Unit ID 1 and 2, Command 2, Data Length,and Data.Check Sum ExampleDFH 80H 60H 47H 01H 01H 08HCommand 1 Unit ID 1 Unit ID 2 Command 2 Data Length Data Check SumTotal 208H2) Error Processing• When the communication interval is vacant for morethan 4 ms, thereafter a received Command 1 will berecognized. If, at this time, meaningful data cannotbe recognized, that data will not be recognized (asvalid data).• An ACK will not be returned unless the receive dataerror, the check sum error, and the receive data are alltaken in.