NEC PlasmaSync 42VP4D User Manual page 59

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.
Check Sum Example
DFH
Command1 Unit ID1
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.
80H 60H
Unit ID2
Total 208H
47H 01H
Command2 Data Length
6
01H 08H
Data Check Sum