NEC 4210W user manual Communication Format, Command, Unit ID 1 and Unit ID, Check Sum Example

Communication Format

8 bit 8 bit 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 PlasmaSync 4210W 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.

39