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CHAPTER10 CPU MODULE PROCESSING TIME
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10
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10.1 Scan Time
10.1.2 Time required for each processing included in scan time
(6) Device data latch processing time
When the latch range is set in the Device tab of the PLC parameter dialog box
*1 *2 *3
, the processing
time shown in Table10.12 is required.
Each N1, N2, and N3 in the table indicates the following:
• N1: Number of devices specified to be latched (Count the latch range (1) and the latch
range (2) as different devices.)
• N2: Number of bit device points specified to be latched
•
N3: Number of word device points specified to be latched
*1: When setting the latch range of the timer (T), retentive timer (ST), and counter (C), one point for word device and two points for bit device
are occupied per point.
*2: The case where the points are set for the latch relay (L) is included.
*3: The scan time will not increase if the latch range is set for the file register (R, ZR), extended data register (D), or extended link register
(W).
To shorten the scan time, minimize the number of latch points.
The number of latch points can be reduced by performing the following.
• Move data to be latched to the file register.
• Store device data that is updated less frequently to the standard ROM with the SP.DEVST instruction. (The device
data stored in the standard ROM can be read with the S(P).DEVLD instruction.)
QCPU Programming Manual (Common Instructions)
Table10.12 Processing time when the latch range is set
CPU module Processing time
Q00UJCPU, Q00UCPU, Q01UCPU
(4.4 N1) + (0.12 (N2 16 + N3)) s
Q02UCPU
(4.0 N1) + (0.12 (N2 16 + N3)) s
Q03UDCPU, Q03UDECPU
(3.0 N1) + (0.12 (N2 16 + N3)) s
Q04UDHCPU, Q06UDHCPU, Q10UDHCPU, Q13UDHCPU, Q20UDHCPU,
Q26UDHCPU, Q04UDEHCPU, Q06UDEHCPU, Q10UDEHCPU, Q13UDEHCPU,
Q20UDEHCPU, Q26UDEHCPU
(3.0 N1) + (0.05 (N2 16 + N3)) s