Mitsubishi MELSEC Q Series Reference Manual page 53

Transmission time (T1) = (Transmission delay time + 1 link scan time or internal processing time)  (n + 1)
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2 DATA COMMUNICATION USING THE MELSEC COMMUNICATION PROTOCOL
(2) For MELSECNET/H (Remote I/O network) and MELSECNET/10
(Remote I/O network)
1
Internal processing time C24 : Approximately 50 ms, E71 : Approximately 30 ms
1 Refer to the applicable section for the transmission delay time in the reference
manual (remote I/O network) for the network system.
• When performing initial communication for the applicable station after
2
link begins.
• When communicating with stations other than the 16 last stations
communicated with.
• When the number of stations communicated with is less than 16 and
communication is performed for the second time.
• When communicating for the second time to one the 16 last stations
communicated with.
3 If the online change setting is disabled in the C24/E71, add this value only when
writing data from the external device.
(The online change status is set in the switch setting parameter for the C24 and
in the operation setting parameter for the E71 using the programming tool.)
(Example)
Loading the C24 on a station on MELSECNET/H (remote I/O network) and reading
the device memory of other station on the same MELSECNET/H.
(When the number of stations communicated with is eight and communicating for
the second time at the following processing time/settings.)
• Sm : Scan time for the sequence program in the remote master station 12 ms
• m : Link refresh time for the remote master station 5 ms
• LS : Link scan time 9 ms
In the (Example), transmission time (T1) is calculated as follows since (Sm) > (LS).
(When the master station is station 1)
Transmission time (T1) = {(12 + 5)
(101 ms)
Causes of transmission time (T1) delay
When a command that takes two scans to send is issued, the transmission time is
twice the value obtained by the above expression.
For the case when another module or programming tool simultaneously requests
access to the same Q/L/QnACPU, refer to REMARKS in Section 2.4.
For more detailed information about the network system, refer to the Q
corresponding MELSECNET/H Network System Reference Manual (Remote I/O
network).
POINT
Data transmission to the programmable controller CPU of stations on
MELSECNET/H other than the local station may be delayed considerably
depending on conditions.
The transmission delay time can be kept short by limiting communication between
an external device and the programmable controller CPU to stations on which the
C24/E71 is loaded and communicating with programmable controller s on other
stations by data link (LB, LM).
When this value is more than
the internal processing time.
3 + 50} 1
(Sm · m)
2 3
n=6
n=1
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