NEC XP29 Plus - Manual (Page 28)

Command Communication Sequence
When external equipment such as a personal computer gives the command to
the XP29 Plus/XM29 Plus, the XP29 Plus/XM29 Plus returns an ACK. So
make sure that the external equipment receives this ACK.
The XP29 Plus/XM29 Plus returns an ACK if it has received the command
correctly.
If it has not received the command correctly due to data error, it will return
nothing. Therefore, when the external equipment send a command, make
sure that it received the ACK.
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Command sending/receiving sequence
Command reference
You can control the main functions from external equipment such as personal
computer using the PC/EXT CTL terminals. The following sections explain the
interface.
Interface Condition
• RS-232C
• Baud rate ------------------------- 9600 bps
• Data length ----------------------- 8 bits
• Parity ------------------------------- Odd parity
• Stop bit ---------------------------- 1 bit
• Communications mode -------- Full duplex
Command 1 ........ Code based on the command system
UNIT ID ............... Code allocated to each equipment (Allocate 80H to the
XP29 Plus/XM29 Plus)
Command 2 ......... Code allocated to the main functions of the XP29 Plus/XM29
Plus
Data Length ........ Number of bytes of the data that is transmitted
Data .................... Data transmitted
Check Sum ......... Lower eight digits of sum total of the first byte to the byte
immediately before the last.
Control Data Format
8bit 8bit 8bit 8bit 8bit 8bit 8bit 8bit
Command 1
UNIT ID
Command 2
Data length
Data Check Sun
External equipment
(PC)
XP29 Plus/XM29 Plus
Command
ACK