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1.4.4
Characteristic data of open communications services (SEND/RECEIVE
interface) over FDL connections
General characteristic data
The characteristic data is important when operating FDL connections (specified, free layer 2
(SDA and SDN), broadcast, multicast):
Characteristic
Total number of FDL connections that can be
operated.
Size of the transferable data area on FDL
connections.
Execution times of the program blocks AG_SEND / AG_RECV
The following table will help you to calculate the CPU cycle times (OB1) for FDL connections.
The table contains the execution time of the FCs (FC AG_SEND, FC AG_RECV) required for DP
processing on the S7-300 / C7-300 CPU.
Component
Execution time on the CPU
314C-2DP (6ES7 314-6CF00-
0AB0)
Execution time on the CPU 317-
2PN/DP (6ES7 317-2EJ10-0AB0)
Time response on FDL connections
Refer to the following table for transmission rates with FDL connections dependent on the
following parameters:
• Frame length (number of bytes)
• CPU type
The values were measured while sending or receiving successively (at a transmission rate of
1.5 Mbps; bus profile standard; 9 nodes).
Table 1- 1
Frame length
8 bytes
128 bytes
240 bytes
CP 342-5
Equipment Manual, 01/2023, C79000-G8976-C146-11
Explanation / values
Per AG_SEND block call:
•
<5.1 ms at <=240 bytes
Per AG_SEND block call:
•
<2.4 ms at <=240 bytes
Number of FDL frames per second for CPU 317
Application and functions
1.4 Performance data and behavior in operation
Explanation / values
16 max.
1-240 bytes maximum per specified FDL
connection (for sending and receiving):
Free Layer 2, broadcast and multicast:
Up to 236 bytes of user data can be transferred
per job. The job header occupies an additional 4
bytes.
Per AG_RECV block call:
•
<5.7 ms at <=240 bytes
Per AG_RECV block call:
•
<2.8 ms at <=240 bytes
Number of FDL frames per second
140 / s
138 / s
135 / s
15
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