Omron SYSMAC CS1W-SCB41-V1 Operation Manual page 187

Setup Area Allocations
RS/CS Flow Control
Half-duplex
Communications
Command
SD signal
RD signal
RS signal
RS signal ON
while RECV
command is
executed.
1,2,3...
Full-duplex Mode
158
With CS/CJ-series half-duplex protocol macro communications (see note), or
with C200HX/HG/HE protocol macro communications, flow control can be
released by turning ON the RS signal (CS signal at the communications part-
ner) while the RECV command is being executed. The timing of this operation
is shown below. (Signal names used below are those at the Serial Communi-
cations Board.)
PMCR(260) instruction
RS turned OFF
after 0.1 to 4 ms
Data received before
SEND is completed is
discarded.
1. With protocol communications in half-duplex mode, the RS signal is ON
only while the RECV command is being executed.
2. The receive data (RD signal) from the communications partner is initially
stored in the reception buffer.
3. The data in the reception buffer is analyzed, and a search is performed for
data matching an expected message registered with the RECV command.
4. When matching data is found, the RS signal is turned OFF. The search
starts after the final data has been received. It takes between 100 µ s and
4 ms from starting the search until the RS signal turns OFF.
5. While the SEND command is being executed, and while the PMCR(260)
instruction is not being executed, the RS signal stays OFF and receive data
is discarded.
Note RS/CS flow control in half-duplex mode is supported only by CS-series Serial
Communications Boards/Units manufactured on or after December 20th,
1999. With earlier models, half-duplex mode will operate in the same way as
full-duplex mode.
Lot No: 20Z9 Manufactured on December 20th, 1999
The year is indicated with the last digit. In this case, "9" indicates "1999."
Month of manufacture. October, November, and December are indicated
with X, Y, and Z respectively. In this case, the month is "December."
Day of manufacture. In this example, the day is "20."
There is a 2.5-Kbyte reception buffer for each serial port in a CS/CJ-series
Serial Communications Board or Unit. When using flow control, initiate flow
control after receiving about 2 Kbytes, and then release control after process-
ing all but 0.5 Kbytes of receive data. Up to 1,000 bytes (500 words) of data
PMCR(260)
instruction
Data received while the PMCR(260)
instruction is not being executed is
discarded (controlled by turning
OFF the RS signal).
The OFF status of the RS signal is
maintained after execution of the
PMCR(260) instruction.
Section 5-2