Omron CS1W-ETN21 - Manual (Page 106)

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CIO Area Allocations Section 4-1
Receiving Flag (Bit 1)
Turns ON when a receive request is received either by control bit manipulation
or the CMND(490) instruction, and turns OFF again when the receive pro-
cessing has been completed. When CMND(490) is used, the Results Storage
Error Flag (bit 14) will turn ON at the same time as the Receiving Flag turns
OFF if there is an error in the Results Storage Area designation.
Sending Flag (Bit 2)
Turns ON when a send request is received either by control bit manipulation
or the CMND(490) instruction, and turns OFF again when the send process-
ing has been completed. When CMND(490) is used, the Results Storage
Error Flag (bit 14) will turn ON at the same time as the Sending Flag turns
OFF if there is an error in the Results Storage Area designation.
Closing Flag (Bit 3)
Turns ON when a close request is received either by control bit manipulation
or the CMND(490) instruction, and turns OFF again when the close process-
ing has been completed. When CMND(490) is used, the Results Storage
Error Flag (bit 14) will turn ON at the same time as the Closing Flag turns OFF
if there is an error in the Results Storage Area designation.
Data Received Flag (Bit 13)
This bit turns ON when data is received from a remote node at an open TCP
socket. Linked to this flag, the number of bytes of data saved in the reception
buffer is stored in Number of Bytes Received at TCP Socket in the words allo-
cated in the DM Area. The bit is turned OFF when a receive request is made
by either bit manipulation or the CMND(490) instruction. If any data remains in
the reception buffer after the receive request processing is complete, the
number of bytes is stored in Number of Bytes Received at TCP Socket and
the Data Received Flag turns ON again.
The status of this flag is checked before a receive request is executed.
Results Storage Error Flag (Bit 14)
Turns ON if there is an error in the Results Storage Area for a socket service
request (open, receive, send, close) made using CMND(490). This flag turns
ON at the same time as the services request processing flags (bits 0 to 3) turn
OFF. It remains ON until the next services request is received, and then it
turns OFF again. When this flag turns ON, check the set values in the Results
Storage Area.
The Results Storage Error Flag does not operate when socket services are
requested by control bit manipulation.
TCP/UDP Open Flag (Bit 15)
Remains ON while a socket is open by means of control bit manipulation or
the CMND(490) instruction. In the case of TCP, it indicates a connection.
When the socket is closed, this flag turns OFF again. (If the socket did not
close properly, the flag remains ON.)
Check to be sure that this flag is ON before executing a send or receive
request.