37
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 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
60H
47H
01H
01H
08H
Command 1 Unit ID 1 Unit ID 2
Command 2 Data Length
Data
Check Sum
Total
208H
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.
○
○
8 bit 8 bit 8 bit 8 bit 8 bit 8 bit
8 bit 8 bit
▲
Plasma monitor
External equipment
e.g., Personal computer
Running Sense
Running Sense
Running Sense
Communications Flow
The plasma monitor regularly transmits a Running Sense
command at an interval of approximately 1 second.
(Running Sense command: 1FH 60H E0H 88H 00H E7H)
This command is used to recognize optional equipment.
The return of an ACK is not required when external equip-
ment such as a personal computer has been connected.
Note that destruction of this data is recommended when it
is taken in.
When various commands are to be sent from external equip-
ment such as a personal computer, the plasma monitor is
always receive enabled.
Note that when an ACK has not been returned from the
plasma monitor in 1.5 seconds, a resending of the com-
mand is recommended.
