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Communication Format
8 bit 8 bit 8 bit 8 bit 8 bit 8 bit
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 plasma monitor 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.
Check Sum Example
DFH
80H
Command 1 Unit ID 1 Unit ID 2 Command 2 Data Length Data
8 bit 8 bit
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.
40
60H
47H
01H
Total
208H
01H
08H
Check Sum
L
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