NEC 42PD3 Benutzerhandbuch

Together with Command 2, this is a number that distinguishes the
various commands.
For ACK, when bit 2 and bit 3 are both “1”, reception of a sup-
ported command or data is indicated. When bit 2 is “0”, reception
of an unsupported command or data is indicated.
Bit 0 and bit 1 should be set as described below.

(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

bit0

0

0

1

1

bit1

0

1

0

1

When multiple screens are selected

Not used

At time of set ID selection

At time of regular use

1) Checks that received data incorporates both the following

checksum and RS-232C (odd) parity.
The checksum comprises the following aspects of one transmit-
ted 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 recognized.

(2) When the receive data error, checksum error, and the re-

ceive data could not all be taken in, ACK is not returned.

3) Returning an ACK

When command processing exceeds 0.5 seconds following
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 command processing is completed.
When command processing is completed, an ACK2 for which
bit 3 of Command 1 has been set to “1” (at the end of command
processing) is returned every 0.5 seconds until command pro-
cessing is completed. Bit 1 of Command 1 is set to 0 ; when the
UA2 setting is FFH, it is possible to simultaneously operate all
sets connected in cascade and as a result, ACK is not returned.

When various commands are sent from a personal computer (PC)
or other external equipment, the display is always 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

9FH

40H

4FH

01H

01H

30H

Command 1

Unit ID

Command 2

Data Length

Data

Check Sum

▲

Personal computer
PC or other external equipment

* When normally selecting one screen, ID or multiple

screen(VIDEO WALL), set bit 0 and bit 1 of Command 1.

Example: CFH for powering on
(Command 1)
CFH

→ 1111 1111 (CFH): At time of regular use

1111 1110 (CEH): Not used
1111 1101 (CDH): At time of set ID selection
1111 1100 (CCH): When multiple screens are selected

The same goes for 0FH, 4FH, 8FH and DFH other than Command
1.

1) Unit ID1: Sets a number corresponding to the various sets ID (1

through 4) when multiple screens are selected, and to 1 through
256 at the time of set ID selection. “00H” must be output when
the ID is not set.

2) Unit ID2: Makes settings on the occasion of simultaneously

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

Together with Command 1, this is a number that distinguishes the
various commands.