478
Cycle Time
Section 7-3
7-3
Cycle Time
7-3-1
Overview
The processes involved in a single execution cycle are shown in the following
table, and their respective processing times are explained.
Note
1.
Servicing Inner Boards with control functions involves transferring data be-
tween the CPU Unit and High-speed Counter, Pulse I/O, Absolute Encoder
Interface, Analog Setting, and Analog I/O Boards.
2.
Servicing Inner Boards with communications functions involves transfer-
ring data between the CPU Unit and a Serial Communications Board.
3.
The percentages can be changed in the PC Setup (DM 6616: Servicing
time for RS-232C port, DM 6617: Servicing time for peripheral port). When
the RS-232C port, peripheral port, or Serial Communications Board port 1
or 2 is used, the time will be 0.256 min. per port.
Cycle Time and Operation
The effects of the cycle time on CPU Unit operation are as shown below.
Process
Content
Time requirements
Overseeing
Setting cycle watchdog timer, I/O bus check, UM
check, refreshing clock, refreshing bits in SR and
AR areas, servicing Inner Boards with control func-
tions (CQM1H-CPU61 only. See note 1.) etc.
0.7 ms (0.1 ms when a Memory Cassette
equipped with a clock is mounted)
Add an additional 0.1 ms for each Inner
Board (not including a Serial Communi-
cations Board). If there are no Inner
Boards, no additional time is required.
Program execution
User program is executed.
Total time for executing instructions. (Var-
ies according to content of user’s pro-
gram.)
Cycle time calculation
Standby until set time, when minimum cycle time is
set in DM 6619 of PC Setup.
Calculation of cycle time.
Almost instantaneous, except for standby
processing.
I/O refresh
Input Unit’s input information is read to input bits.
Output information (results of executing program) is
written to Output Unit’s output bits.
Number of input words
×
0.01 ms
Number of output words
×
0.005 ms
RS-232C port servicing
Devices connected to RS-232C port serviced.
(Except for CQM1H-CPU11.)
5% or less of cycle time (see note 3)
Peripheral port servicing
Devices connected to peripheral port serviced.
5% or less of cycle time (see note 3)
Inner Board with commu-
nications functions ser-
vicing (See note 2.)
When a Serial Communications Board is mounted,
commands from the Board are processed.
(CQM1H-CPU51/61 only.)
0.4 ms + processing time per port
The processing time per port is the mini-
mum of 0.256 or 0.05
×
cycle time calcu-
lated above.
If there is no Serial Communications
Board mounted, this time will be 0 ms.
Communications Unit
servicing
When a Controller Link Unit is mounted, com-
mands from the Board are processed. (CQM1H-
CPU51/61 only.)
For the CQM1H-CLK21, 4 ms max.
If a Communications Unit is not con-
nected, this time will be 0 ms.
Cycle time
Operation conditions
10 ms or longer
TIMH(15) may be inaccurate when TC 016 through TC 511 are used (operation will be normal for TC
000 through TC 015) (see note 1).
20 ms or longer
Programming using the 0.02-second Clock Bit (SR 25401) may be inaccurate.
100 ms or longer
Programming using the 0.1-second Clock Bit (SR 25500) may be inaccurate. A CYCLE TIME OVER
error is generated (SR 25309 will turn ON) (see note 2).
The TIMER (TIM) and TOTALIZING TIMER (TTIM) instructions may not be accurate.
120 ms or longer
The FALS 9F monitoring time SV is exceeded. A system error (FALS 9F) is generated, and operation
stops (see note 3).
200 ms or longer
Programming using the 0.2-second Clock Bit (SR 25501) may be inaccurate.
