NEC 4205W User Manual

8 bit

○

Check Sum Example

9FH

80H

60H

47H

01H

08H

Command 1 Unit ID 1

Unit ID 2

Command 2 Data Length Data

Check Sum

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 PlasmaSync 4205W 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.

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.