423
5-36-7 About SYSMAC NET Link/SYSMAC LINK Operations
SEND(192), RECV(193), and CMND(194) are based on command/response
processing. That is, the transmission is not complete until the sending node re-
ceives and acknowledges a response from the destination node, unless the re-
sponse function is disabled in the control word or data is being broadcast to all
nodes in a network. Refer to the
SYSMAC NET Link System Manual
or
SYS-
MAC LINK System Manual
for details about command/response operations.
If more than one network instruction (SEND(192)/RECV(193)/CMND(194)) is
used through one port, the following flags must be used to ensure that any pre-
vious operation has completed before attempting further network instructions.
Flag Functions
Port #0 to #7
Enabled Flags
(A50200 to A50207)
Enabled Flags A50200 to A50207 are OFF during
network instruction execution for ports #0 to #7,
respectively. Do not start a network instruction for a port
unless the corresponding Enabled Flag is ON.
Port #0 to #7
Execution Error Flags
(A50208 to A50215)
OFF following normal completion of a network
instruction (i.e., after reception of response signal)
ON after an unsuccessful network instruction attempt.
Error status is maintained until the next network
instruction.
Error types:
Time-out error (command/response time greater than
the response monitoring time set in the control words)
Transmission data errors
Port #0 to #7
Completion Codes
(A503 to A510)
A503 to A510 contain the completion codes for errors
that occur during network instruction execution for ports
#0 to #7, respectively. The code for normal completion of
a network instruction is 0000. Refer to the
SYSMAC
NET Link System Manual
or
SYSMAC LINK System
Manual
for details about error codes.
Timing
Instruction
received
Transmission
completes
normally
Instruction
received
Transmission
error
Instruction
received
Enabled
Flag
Execution
Error Flag
Data is transmitted on a network when SEND(192), RECV(193), or CMND(194)
is executed. Final processing for transmissions/receptions is performed during
servicing of Link Units.
Instruction execution and peripheral device servicing are processed in parallel,
thus data from network instructions might not be processed synchronously. To
synchronize data processing, set the PC to synchronous execution or use the
IOSP(187) and IORS(188) instructions.
To ensure successful SEND(192)/RECV(193) operations with more than one in-
struction for a single port, your program must use the Enabled Flag and Error
Flag to confirm that execution is possible. The following program shows one ex-
ample of how to do this for port 4 in a SYSMAC NET Link System. The program is
effective when both bit 000000 and the Port 4 Enable Flag (A50204) are ON.
Data Processing for
Network Instructions
Programming Example:
Multiple Instructions
Network Instructions Section 5-36
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