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MELSEC-
A
3 SPECIFICATIONS AND FUNCTIONS
(2) When master module is QJ61BT11N
(a) Calculation expression
Details Calculation expression (Unit: ms)
Master module D75P2
(write (RIWT command))
OT + LS {BC + (number of write points
*1
+ 16)/72
*2
1.13}
Master module D75P2
(read (RIRD command))
OT + LS
{BC + (number of read points
*1
+ 16)/16
*2
1.067}
*1: Set in word unit
*2: Rounded up to the one place
OT : QCPU dedicated command processing time
QnCPU : 1[ms]
QnHCPU : 0.5[ms]
SM : Scan time of master module sequence program
LS : Link scan time (refer to the Master Module User's Manual)
BC
156kbps 625kbps 2.5Mbps 5Mbps 10Mbps
6 7 9 11 12
(b) Calculation example
The following example calculates the transmission delay time taken when
"
Md.30
Machine feed value" (2 words) is read from the D75P2 when the
Q06HCPU is used.
When SM is 20ms, transmission speed is 10Mbps, and only one D75P2 is
connected
LS : 1.8ms (for the calculation expression, refer to "(2) Calculation
example in Cyclic transmission")
Transmission delay time = OT + LS
{BC + (2 + 16)/16 1.067}
= 0.5 + 1.8
{12 + (2 + 16)/16 1.067}
= 0.5 + 1.8
14.134
25.9[ms]
However, when data is read from the buffer memory whose update timing is at
56.8ms intervals
*1
, data after a maximum of 25.9 + 56.8 = 82.7ms is read as
shown below depending on the read timing.
*1
Md.37
update timing is at 910ms intervals.
D75P2 update timing
56.8ms 56.8ms 56.8ms 56.8ms
Md. 30 Machine feed value
1)
Read
execution
Read
complete
25.9+1) (ms)