Plc Cycle Time Performance; I/O Response Time - Omron SYSMAC CS Series Operation Manual

I/O Communication Characteristics
6-5-5

PLC Cycle Time Performance

Note
6-5-6

I/O Response Time

PROFIBUS DP Cycle >
PLC Cyclic Refresh
PLC Cycle
Slave I/O data refresh
PROFIBUS Cycle
Slave I/O data refresh
T
ON
178
The cyclic refresh time is the time required for I/O data to be exchanged
between the PLC CPU Unit and the PROFIBUS Master Unit. The PLC CPU
Unit cyclic refresh time is increased when a PROFIBUS Master Unit is
mounted, as shown below.
PLC CPU type
CS1/CJ1G-H CPU
CS1/CJ1H-H CPU
CJ1M
1. The number of words refreshed is the total number of words in the I/O area
that are used by the slave devices, including any unused words that may
be present in I/O mapping gaps (refer to section 6-5-2 Mapping I/O Data).
2. The number of words refreshed also includes the 25 CIO status and com-
mand words.
3. If FINS message communications is being performed, add the number of
words used in the message communications to the above number of words
when messages are being processed.
4. For details about cyclic refresh time or PLC cycle time, refer to operation
manual of the PLC.
Note To avoid missing input data or output data, the PLC cyclic refresh time must
be at least 3 ms.
The maximum I/O response time is defined as the time from the moment an
input on a slave device with the lowest PROFIBUS address is switched ON
(OFF) until the moment the output on a slave device with the highest PROFI-
BUS address is switched ON (OFF).
The figure below shows the timing in case the PROFIBUS DP cycle > PLC
cyclic refresh.
Instruction Instruction Instruction
Execution Execution Execution
T T
PB,Cyc PB,Cyc
IN
T
M,Proc
PROFIBUS Master Unit cyclic refresh time (ms)
0.5 + 0.001 × the number of I/O words (See notes)
0.3 + 0.001 × the number of I/O words (See notes)
0.5 + 0.001 × the number of I/O words (See notes)
Instruction Instruction
Execution Execution
T T
PLC,Cyc PLC,Cyc
+ T T
M, Rrf PLC,Rf
Section 6-5
Instruction Instruction Instruction
Execution Execution Execution
T T
PB,Cyc PB,Cyc
T
M,Proc
T
OUT
ON