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Socket Service Status Section 6-6
6-6-2 DM Area Allocations
The following DM Area words are allocated in the CPU Bus Unit Area in the
DM Area. The beginning word m is calculated by the following equation.
Beginning word m = D30000 + (100 x unit number)
■ Number of Bytes Received at TCP Socket (Ethernet Unit to CPU Unit)
The number of bytes of data saved in the reception buffer at the TCP socket is
stored in the TCP Connection Status words. The Data Received Flag in the
CIO Area turns ON/OFF in response to the status of these words. When the
dedicated control bits (switches) are manipulated or the receive request is
sent by executing the CMND(490) instruction, the values of these words are
temporarily set to 0000 hexadecimal.
If any data remains in the reception buffer after the receive request processing
is complete, the number of bytes is stored in the Number of Bytes Received at
TCP Socket and the Data Received Flag turns ON again.
Receive requests should be executed after confirming that the required data
is contained in the number of bytes received.
15141312 10987654321011
---------
Data Received/Requested Flag
Receiving Flag
Sending Flag
Closing Flag
Opening Flag
Results Storage Flag
TCP Connection/UDP Open Flag
Bit Switch Status Manipulated
by
Unit operation
0 Opening Flag ON Unit Turns ON when an open request is received.
OFF Turns OFF when open processing has been completed.
1 Receiving Flag ON Turns ON when a receive request is received.
OFF Turns OFF when receive processing has been completed.
2 Sending Flag ON Turns ON when a send request is received.
OFF Turns OFF when send processing has been completed.
3 Closing Flag ON Turns ON when an close request is received.
OFF Turns OFF when close processing has been completed.
13 Data Received Flag ON Turns ON when data from a remote node has been received at an
open TCP socket.
OFF Turns OFF when receive processing has been requested for an
open TCP socket.
14 Results Storage Error
Flag
ON Turns ON if there is an error in the Results Storage Area specified
for the socket service request command to the Ethernet Unit.
This flag turns ON at the same time as any of the services request
processing flags (bits 0 to 3) turn ON again (i.e, at completion of
processing).
OFF Turns OFF when the next request is received.
15 TCP Connection/UDP
Open Flag
ON Turns ON when UDP open processing has been completed or when
a TCP connection is made.
OFF Turns OFF when close processing has been completed. (Will
remain OFF when open processing ends in an error.)
15141312 10987654321011
m+1 to m+8
Number of Bytes Received (0000 to 07C0 hexadecimal)