NEC 42PD2, 50PD1 Communication Parameters, Communication Format, Command, Unit ID 1 and Unit ID

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

Communication Format

8bit

8bit

8bit

8bit

8bit

8bit

8bit

8bit

Check

Sum

Data

Data length

Command 2

UNIT ID 2

UNIT ID 1

Command 1

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.

bit0	bit1
0	0	When multiple screens are selected
0	1	Not used
1	0	At time of set ID selection
1	1	At time of regular use

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

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.

Check Sum Example

9FH	40H	4FH	01H	01H	30H
Command 1	Unit ID	Command 2	Data Length	Data	Check Sum
					▲

Total 130H

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

	Personal computer
Plasma display	PC or other external equipment
	Various commands

ACK

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.

53