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MELSEC-Q
6 COMMUNICATION TIME
The master bus cycle time Bc can be calculated as:
Number of the slave stations
Bc = Max (MSI, (Pt (i) + Tsdi (M)) + Lr
i = 1
However,
The largest of A and B = Max (A, B)
Pt (i) = No.i station polling time = Treq(i) + Max Tsdr (i) + Tres (i)
Treq (i) No.i station request transmission time = ((number of output bytes to No.i
s 9) 11)/baud rate
Max Tsdr (i) = No.i station response time ((This value is given in the slave GSD
(DDB) file.)/baud rate
Tres (i) No.i station response transmission time = ((Number of input bytes from No.i
s 9) 11)/baud rate
Tsdi (M) = master request/response processing time (This value is given in the slave
GSD (DDB) file.)/baud rate
The master request/response processing time corresponding to baud rate is as
follows.
Baud rate
9.6
Kbps
19.2
Kbps
93.75
Kbps
197.5
Kbps
500
Kbps
1.5
Mbps
3Mbps 6Mbps
12
Mbps
Master request/response
processing time (ms)
10
15
15
80
80
150
150
150
150
Lr = data refresh time = 1.5 (ms) number of slave stations
MSI = polling cycle minimum cycle (set by GX Configurator-DP)
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