159
Auxiliary Area and CIO Area Allocations Section 5-3
can be stored for each RECV command if 2 Kbytes of receive data is first
stored in the buffer and 1,000 bytes (03E8 Hex) is set as the maximum num-
ber of send/receive data bytes. The timing of this operation is shown below.
(Signal names used below are those at the Serial Communications Board.)
1,2,3... 1. With full-duplex protocol communications, the RS signal is turned OFF
when 2 Kbytes of data has been stored in the reception buffer (i.e., with
0.5 Kbytes remaining).
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, all the previous data is deleted from the re-
ception buffer.
5. If this results in the amount of data stored in the reception buffer dropping
to less than 0.5 Kbytes (i.e., more than 2 Kbytes remaining), the RS signal
is turned ON.
6. Data that is received while the PMCR(260) instruction is not being execut-
ed is discarded.
7. In full-duplex mode, the data left over after the analysis performed with the
last RECV command and any subsequent data received before the next
PMCR(260) execution is discarded. During this interval, RS flow control
cannot be used.
Note Full-duplex mode is supported only by the CS/CJ Series.
5-3 Auxiliary Area and CIO Area Allocations
This section describes the bits and words used by the Serial Communications
Board and Serial Communications Units in the Auxiliary Area and the Soft-
ware Switches and Status Area allocated in the CIO Area.
5-3-1 Auxiliary Area Allocations
Port 1 and Port 2 Port
Settings Change Bits
These bits can be turned ON from the program using the OUT or other
instructions to change communications settings and restart the Serial Com-
munications Board ports. When changing the settings and restarting the port
have been completed, the bit will automatically be turned OFF.
Receive Receive ReceiveSend Send
PMCR(260) instruction PMCR(260) instruction
SD signal
RD signal
RS signal
RS turned ON when
only 0.5 Kbytes in
buffer.
RS signal turned OFF
when 2 Kbytes of data
accumulates in
reception buffer.
Data received from the end of the
last RECV command until the next
PMCR(260) execution is discarded.
The RS signal does not operate.
Command
To Next Page
Loading...
Need help?
General
