Appendix E: Document, others
Appendix E-2 Processing Time
149
FX3U-ENET-ADP User's Manual
B
Version
Information
C
Program
Examples
D
Differences with
FX
3U
-ENET
E
Document,
others
Appendix E-2 Processing Time
Calculate the minimum processing time for MC protocol using the expressions below.
Note that the processing time may become longer depending on the load factor on the network (how
congested the line is), the window size of each connected device, the number of connections used
concurrently, and how the system is configured. Use the values obtained from the expressions below as a
guideline for the processing time when communication is performed using only one connection.
• Minimum processing time of communication using MC protocol (batch read and batch write)
Tfs = Ke + (Kdt Df) + Scr number of scans required for processing + ACK processing time of
external device
Tfs : Time from when Ethernet adapter receives request data from personal computer until it
completes processing (unit: ms)
*1
Ke, Kdt : Constant (refer to the table below)
Df : Number of request data words + number of response data words (Application data part)
Scr : Scan time
*1. The timing sequence from when the Ethernet adapter receives the request data from the personal
computer until it completes processing is shown below.
[Calculation example 1]
Calculate the required time (unit: ms) to complete the processing of a data request from a PC after receiving
it, when the Ethernet adapter and the PC perform TCP/IP communication and read 32 points of ASCII code
data from the data register (D) in the PLC using MC protocol communication.
• Assume that the scan time of the Ethernet adapter installed station is 40 ms:
52.37 + ACK processing time of the external device (ms)
8 + (0.056
(12 + 66)) + 40 1 + ACK processing time of the external device
Command data length = 12 words
Response data length = 66 words
[Calculation example 2]
Calculate the required time (unit: ms) the Ethernet adapter takes to complete the processing of a data request
from a PC after receiving it, when the Ethernet adapter and the PC performs TCP/IP communication and
writes 32 points of ASCII code data to the data register (D) in the PLC using MC protocol communication.
• Assume that the scan time of the Ethernet adapter installed station is 40 ms:
52.37 (ms) 8 + (0.056 (76 + 2)) + 40 1
Command data length = 76 words
Response data length = 2 words
Communication content
Communication using TCP/IP Communication using UDP/IP
Ke Kdt Ke Kdt
Batch read
Data communication using binary code 8 0.054 8 0.059
Data communication using ASCII code 8 0.056 7 0.067
Batch write
Data communication using binary code 9 0.049 7 0.051
Data communication using ASCII code 8 0.056 8 0.051
ACK
END END
ACK
(personal computer)
External device
Ethernet adapter
PLC scan time
Command
message
Step 0 Step 0
(TCP only)
Response
message
(TCP only)
Tfs
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