!
7-30
Section
Communications Instructions
506
N must be BCD from #0000 to #0256. (#0000 to #0061 in Host Link mode)
Description
When the execution condition is OFF, RXD(47) is not executed. When the
execution condition is ON, RXD(47) reads N bytes of data received at the port
specified in the control word, and then writes that data in words D to D+(N
÷
2)–1.
Up to 256 bytes of data can be read at one time.
If fewer than N bytes are received, the amount received will be read.
Note
Refer to
4-1Communications Functions
for details on using the RXD(47) instruc-
tion, setting communications protocol in the PC Setup, etc.
Caution
The PC will be incapable of receiving more data once 256 bytes have been re-
ceived if received data is not read using RXD(47). Read data as soon as pos-
sible after the Reception Completed Flag is turned ON (AR 0806 for the
RS-232C port, AR 0814 for the peripheral port.)
Control Word
The value of the control word determines the port from which data will be read
and the order in which data will be written to memory.
Byte order
0: Most significant bytes first, same word
1: Least significant bytes first, same word
Not used. (Set to 00.)
Port
0: RS-232C port.
1: Peripheral port.
Digit number:
3 2 1 0
The order in which data is written to memory depends on the value of digit 0 of C.
Eight bytes of data 12345678... will be written in the following manner:
MSB LSB
D
1
2
D+1
3
4
D+2
5
6
D+3
7
8
Digit 0 = 0
MSB LSB
D
2
1
D+1
4
3
D+2
6
5
D+3
8
7
Digit 0 = 1
MSB LSB
D
1
D+1
2
3
D+2
4
5
D+3
6
7
Digit 0 = 2
MSB LSB
D
1
D+1
2
3
D+2
4
5
D+3
6
7
Digit 0 = 3
Flags
ER:
The settings in C are not correct.
N is greater than 256.
The PC Setup is not set for no-protocol mode.
RXD(47) is already being executed.
AR 08:
AR 0806 will be turned ON when data has been received normally at the
RS-232C port. Reset when RXD(47) is executed.
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