8-3
Section
SRM1(-V2) Cycle Time and I/O Response Time
539
Cycle Time and Operations
The effects of the cycle time on SRM1(-V2) operations are as shown below.
When a long cycle time is affecting operation, either reduce the cycle time or im-
prove responsiveness with interrupt programs.
Cycle time
Operation conditions
10 ms or longer
TIMH(15) may be inaccurate when TC 004 through TC 127 are used (operation will be normal for
TC 000 through TC 003).
20 ms or longer
Programming using the 0.02-second Clock Bit (SR 25401) may be inaccurate.
100 ms or longer
TIM may be inaccurate. Programming using the 0.1-second Clock Bit (SR 25500) may be inaccu-
rate. A CYCLE TIME OVER error is generated (SR 25309 will turn ON). See note 1.
120 ms or longer
The FALS 9F monitoring time SV is exceeded. A system error (FALS 9F) is generated, and opera-
tion stops. See note 2.
200 ms or longer
Programming using the 0.2-second Clock Bit (SR 25501) may be inaccurate.
Note
1. The PC Setup (DM 6655) can be used to disable detection of CYCLE TIME
OVER error.
2. The cycle monitoring time can be changed in the PC Setup (DM 6618).
Cycle Time Example
The following is an example of a cycle time calculation.
The operating conditions are assumed to be as follows:
User’s program:500 instructions (consists of only LD and OUT)
Cycle time:
Variable (no minimum set)
RS-232C port: Not used.
Max. nodes:
32 nodes and high-speed communications mode
(CompoBus/S communication response time = 0.8 ms)
Peripheral:
0.7 ms
The average processing time for a single instruction in the user’s program is as-
sumed to be 1.16
µ
s. The cycle times are as shown in the following table.
Process
Calculation method
Peripheral port used
Peripheral port not used
1. Overseeing
Fixed
0.18 ms
0.18 ms
2. CompoBus/S end wait
See previous page.
0.00 ms
0.62 ms
3. Input refresh
Fixed
0.02 ms
0.02 ms
4. Program execution
1.16
×
500 (
µ
s)
0.8 ms
0.8 ms
5. Cycle time calculation
Negligible
0.00 ms
0.00 ms
6. Output refresh
0.01
×
1 + 0.005
×
1 (
µ
s)
0.05 ms
0.05 ms
7. RS-232C port servicing
Not required
0.00 ms
0.00 ms
8. Peripheral port servicing
5% of cycle time
0.7 ms
0.00 ms
Cycle time
(1) + (2) + (3) + ...+ (8)
1.75 ms
1.67 ms
Note
1. The cycle time can be read from the PC via a Programming Device.
2. The maximum and current cycle time are stored in AR 14 and AR 15.
3. The cycle time can vary with actual operating conditions and will not neces-
sarily agree precisely with the calculated value.
4. When the peripheral port is used, there is no CompoBus/S end wait time as it
is always 0 or less.
5. CompoBus/S end wait time = 0.8 – 0.18 – 0 – 0 = 0.62 (CompoBus/S com-
munication response time – Overseeing – RS-232C port servicing time –
peripheral port servicing time.
Содержание SRM1 - PROGRAMING 02-2001
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