NEC PlasmaSync 50PD1 - Manuel (Page 53)

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8bit 8bit 8bit 8bit 8bit 8bit 8bit 8bit
Command 1
UNIT ID 1
UNIT ID 2
Command 2
Data length
Data
Check Sum
Command 1
Together with Command 2, this is a number that distin-
guishes the various commands.
For ACK, when bit 2 and bit 3 are both “1”, reception of a
supported command or data is indicated. When bit 2 is
“0”, reception of an unsupported command or data is in-
dicated.
Bit 0 and bit 1 should be set as described below.
Communication Parameters
(1) Communication system Asynchronous
(2) Interface RS-232C
(3) Baud rate 9600 bps
(4) Data length 8 bits
(5) Parity Odd
(6) Stop bit 1 bit
(7) Communication code Hex
Unit ID 1 and Unit ID 2
1) Unit ID1: Sets a number corresponding to the various
sets ID (1 through 4) when multiple screens are se-
lected, and to 1 through 256 at the time of set ID selec-
tion. “00H” must be output when the ID is not set.
2) Unit ID2: Makes settings on the occasion of simulta-
neously operating all sets connected in cascade at the
time of multiple screen mode and at the time of set ID
selection.
Selection of all sets: FFH
At time of regular setting: 00H
bit0
0
0
1
1
bit1
0
1
0
1
Communication Format
When multiple screens are selected
Not used
At time of set ID selection
At time of regular use
Command 2
Together with Command 1, this is a number that distin-
guishes the various commands.
Check Sum (CKS), Error Processing, and ACK
1) Checks for receive data incorporate both the following
checksum and RS-232C (odd) parity.
The checksum comprises the following aspects of one
transmitted or received frame: Command 1, Unit 1 and
2, Command 2, data length, and the lower order 8 bits
of the total data.
2) Error Processing
(1) When the communications interval is 4 ms or
greater, the arrival of a subsequent Command 1
will be recognized. If meaningful data cannot be
discerned at this time, that data will not be recog-
nized.
(2) When the receive data error, checksum error, and
the receive data could not all be taken in, ACK is
not returned.
3) Returning an ACK
When command processing exceeds 0.5 seconds fol-
lowing command reception, an ACK1 for which bit 3
of Command 1 has been set to “0” (during command
processing) is returned every 0.5 seconds until com-
mand processing is completed. When command pro-
cessing is completed, an ACK2 for which bit 3 of
Command 1 has been set to “1” (at the end of com-
mand processing) is returned every 0.5 seconds until
command processing is completed. Bit 1 of Command
1 is set to 0 ; when the UA2 setting is FFH, it becomes
possible to simultaneously operate all sets connected
in cascade and as a result, ACK is not returned.
Communications Flow
When various commands are sent from a personal com-
puter (PC) or other external equipment, the display is al-
ways ready to receive them.
Note that resending of the command is recommended
when an ACK is not returned from the display within 1.5
seconds.
Plasma display
Various commands
ACK
Check Sum Example
9FH 40H 4FH 01H 01H 30H
Command 1 Unit ID Command 2 Data Length Data Check Sum
Total 130H
▲
Personal computer
PC or other external equipment