NEC PlasmaSync 4210W - Manual (Page 46)

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8 bit 8 bit 8 bit 8 bit 8 bit 8 bit 8 bit 8 bit
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Check Sum Example
DFH 80H 60H 47H 01H 01H 08H
Command 1 Unit ID 1 Unit ID 2 Command 2 Data Length Data Check Sum
Communication Format
Command 1
Unit ID 1
Unit ID 2
Command 2
Data length
Data
Check sum
Command 1
Command 1, along with command 2, is a number used to distinguish each command.
In the case of ACK, when the lower order 4 bits is FH (as in 3FH and 7FH), this indicates that the commands and data of
the supported equipment have been received. When the lower order 4 bits is BH (as in 3BH and 7BH), this indicates that
unsupported commands and data have been received.
Unit ID 1 and Unit ID 2
Unit ID 1 and unit ID 2 are numbers used to identify the equipment that is to be connected.
60H is used for the PlasmaSync 4210W and 80H is used for external control equipment such as a personal computer.
1) Unit ID 1: Indicates the equipment sending the signal
2) Unit ID 2: Indicates the equipment receiving the signal
Command 2
Command 2, along with command 1, is a number used to distinguish each command.
Check Sum (CKS), Error Processing, and ACK
1) The check sum described below and RS-232C odd parity are used together for a check of the received data.
The check sum is the lower order 8 bits of one frame of sent or received data comprising the sum total of Command 1,
Unit ID 1 and 2, Command 2, Data Length, and Data.
Total 208H
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2) Error Processing
• When the communication interval is vacant for more than 4 ms, thereafter a received Command 1 will be recognized.
If, at this time, meaningful data cannot be recognized, that data will not be recognized (as valid data).
• An ACK will not be returned unless the receive data error, the check sum error, and the receive data are all taken in.