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6-4SectionUsing No-protocol Communications
102
6-4 Using No-protocol Communications
6-4-1 TRANSMIT – TXD(––) and RECEIVE – RXD(––)
This section describes using TXD(––) and RXD(––) for no-protocol communica-
tions.
TRANSMIT – TXD(––) in No-protocol Mode
First source word
Control word
Number of bytes
(4 digits BCD, 0000 to 0256)
TXD(––)
S
C
N
Control Word: C
Byte order 0: Most significant bytes first
1: Least significant bytes first
Not used. (Set to 0.)
Port 0: RS-232C port on CPU Unit
1: Port 1 on Serial Communications Board
2: Port 2 on Serial Communications Board
Not used. (Set to 0.)
15 00
00
The specified number of bytes will be read starting from S and transmitted
through the specified port.
• Up to 256 bytes of data can be sent each time the instruction is executed.
• The bytes of source data shown below will be sent in the following order.
If most significant bytes first is specified (0): 12345678..
If least significant bytes first is specified (1): 21436587..
MSB LSB
S12
S+1 3 4
S+2 5 6
S+3 7 8
Communications parameters are set in the PC Setup settings for the Serial
Communications Board. Refer to information in the CQM1H Programming
Manual on serial communications and TXD(––) for details.