Panasonic FP2 ET-LAN, Техническое руководство

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15.5 Minimum Transmission Delay Time
The minimum transmission processing time for MEWTOCOL communication and transparent
communication is determined using the formulas below. This calculation serves as a general guide for
the transmission time, assuming that there is one connection being used, no other nodes exist on the
network, and 1:1 communication is being carried out. The actual transmission time may be longer,
depending on the load ratio of the network, the transmission line environment, the number of
connections being used, the system configuration, and the window size.
For the processing tome of the partner node, please refer to the instruction manual and other
documentation for that particular device.
MEWTOCOL communication
This is a guide to the transmission processing time when the computer is issuing commands and the ET-
LAN unit is returning responses. It indicates the time from the point that the ET-LAN unit receives the
command, to when it sends the response.
Transmission processing time when using the computer link function
PLC being
used Communication
processing method Transmission processing time (calculation formula)
FP2 CPU Read contact/data
(RD/RCS command) 0.032 x no. of command and response data bytes + 4.8 +
CPU scan time (ms)
Write contact/data
(WD/WCS command) 0.046 x no. of command and response data bytes + 4.3 +
CPU scan time (ms)
FP2SH
CPU Read contact/data
(RD/RCS command) 0.015 x no. of command and response data bytes + 8.7 +
CPU scan time (ms)
Write contact/data 0.022 x no. of command and response data bytes + 6.4 +
CPU scan time (ms)
Transmission processing time when using the data transmission function
PLC being
used Communication
processing method Transmission processing time (calculation formula)
FP2 CPU Read contact/data 0.009 x no. of command and response data bytes + 12.4 +
CPU scan time (ms)
Write contact/data 0.007 x no. of command and response data bytes + 8.5 +
CPU scan time (ms)
FP2SH
CPU Read contact/data
0.013 x no. of command and response data bytes + 5.8 +
CPU scan time (ms)
Write contact/data 0.011 x no. of command and response data bytes + 4.2 +
CPU scan time (ms)
The above calculation formulas are used for both TCP/IP and UDP/IP.
The number of command data bytes and response data bytes are the total number of bytes, including
the MEWTOCOL format header and all of the data.
[Example]
When using the FP2 CPU and reading 100 words of data with the computer link function (RD command),
assuming a CPU scan time of 5 ms, the following would result:
Transmission processing time = 0.032 x (32 command bytes + 421 response bytes) + 4.8 + 5 (ms) =
Approx. 24 (ms)