
B-64164EN/01 SPECIFICATION 3.MESSAGE TRANSMISSION
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NOTE
1 Transmission starts when the user program writes
0001h into the transmission request/response flag.
Therefore, set 0001h after setting data in all other
interface areas.
While the transmission request/response flag is
0001h, the user program must not rewrite data in
this interface area.
If the content of this area is rewritten, message
transmission cannot sometimes end normally.
2 When the message transmission service ends, the
system returns 8000h or a larger value to the
transmission request/response flag.
At the time of normal end, 8000h is returned; at the
time of abnormal end, a value other than 8000h is
returned. When an abnormal end occurs, check
the value and correct the cause.
For error codes returned by the system, see Table
3-3.
3 After a message transmission request is made, this
interface does not allow the next transmission
request to be made until a response message is
received or an error occurs. So, if a response
message cannot be received for a cause on the
server, the next message transmission request
cannot be made until the power is turned off. In
such a case, the cancel flag allows the system to
exit from the response message wait state and wait
for the next message transmission request. The
purpose of this cancellation is just to allow the
system to accept the next message transmission
request. This cancellation is not intended to cancel
message transmission with the FL-net function.
(The FL-net function does not have a function for
canceling message transmission.) This means that
when this cancellation function is used, the
response message for the previous message
request may be treated as a response to the next
message request by mistake.
4 If a response message is received before ACK is
returned in response to a request message, the
request status (R_STS) is sometimes not set to 01h.