![](/images/new-backgrounds/1193384/193384363x1.webp)
Precautions in Using Socket Services | Section |
Note 4: When the CPU Unit cycle time is less than 2 ms, A = 27, and when it is 2 ms or more, A = 53
Note 1. The values obtained from the above equations are guidelines for the trans- mission delay time when one socket in the Ethernet Unit is used only. The execution time required for the user program is not included.
2.The communications time for the remote nodes depends on the device be- ing used. For remote nodes that are not Ethernet Units, calculate the com- munications time according to the device's operation manual.
3.The actual operating environment can cause transmission delays larger than those calculated with the methods given here. Among the causes of longer delays are the following: traffic on the network, window sizes at net- work nodes, traffic through the Ethernet Unit (e.g., simultaneous servicing of multiple sockets and socket service communications, etc.), and the sys- tem configuration.
4.The above values are guidelines when the default (4%) for the uniform pe- ripheral servicing time in the PLC System Setup is used.
5.By increasing the value of the uniform peripheral servicing time, the maxi- mum transmission delay time for socket services can be shorter.
Example: When using TCP socket services between two PLCs
CPU Unit cycle time (local node) = 5 ms
CPU Unit cycle time (remote node) = 10 ms
Item | Calculation |
|
|
Reception processing | 5 ⋅ 2 + 512 ⋅ 0.001 + 53 = 63.512 ms ≈ 63.5 ms |
time (local node) |
|
Transmission processing | 5 ⋅ 2 + 512 ⋅ 0.001 + 53 = 63.512 ms ≈ 63.5 ms |
time (local node) |
|
Transmission processing | 10 ⋅ 2 + 512 ⋅ 0.001 + 53 = 73.512 ms ≈ 73.5 ms |
time (remote node) |
|
Reception processing | 10 ⋅ 2 + 512 ⋅ 0.001 + 53 = 73.512 ms ≈ 73.5 ms |
time (remote node) |
|
Maximum transmission | 63.5 + 63.5 + 73.5 + 73.5 = 274 ms |
delay |
|
158