Omron C200HX Operation Manual page 352

Serial Communications Instructions
! Caution
Control Word
Digit number: 3 2 1 0
Flags
334
Note RXD(––) is required to receive data via the peripheral port or RS-232C port only.
Transmission sent from a host computer to a Host Link Unit are processed auto-
matically and do not need to be programmed.
The PC will be incapable of receiving more data once 256 bytes have been re-
ceived if received data is not read using RXD(––). Read data as soon as pos-
sible after the Reception Completed Flag is turned ON (SR 26414 for the periph-
eral port, SR26406 for the RS-232C port).
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
1: Least significant bytes first
CTS and DSR signal monitoring
0: Don't monitor CTS and DSR signals.
1: Monitor the CTS signal. (Output to bit 15 of D.)
2: Monitor the DSR signal. (Output to bit 15 of D.)
3: Monitor the CTS and DSR signals. (Output to bits 15 and 14 of D.)
Auxiliary reception port (when DR-15 is 0.)
0: Internal RS-232C port
1: Communications port A
2: Communications port B
Port 0: RS-232C port
1: Peripheral port
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:
Digit 0 = 0
D
D+1
D+2
D+3
ER: The CPU Unit is not equipped with an RS-232C port.
Another device is not connected to the specified port.
There is an error in the communications settings (PC Setup) or the oper-
and settings.
Indirectly addressed DM word is non-existent. (Content of DM word is
not BCD, or the DM area boundary has been exceeded.)
The destination words (D to D+(N÷2)–1) exceed the data area.
Peripheral Port
26414: SR 26414 will be turned ON when data has been received normally at
the peripheral port and will be reset when the data is read using
RXD(––) is executed.
266: SR 266 contains the number of bytes received at the peripheral port and
is reset to 0000 when RXD(––) is executed.
RS-232C Port
MSB LSB
1 2
3 4
5 6
7 8
Section 5-27
Digit 0 = 1
MSB LSB
D 2 1
D+1 4 3
D+2 6 5
D+3 8 7