56
Remote Communication Characteristics
Section 3-5
Maximum I/O Response
Time
The maximum I/O response time (T
MAX
) is the total of the following terms:
T
MAX
= T
IN
+ 2×T
SL
+ T
SL-CI
+ T
SL-CO
+ 2×T
RM
+ 2×T
PLC
+ T
RF
+ T
OUT
T
IN
: The Input Unit's ON (OFF) delay
T
OUT
: The Output Unit's ON (OFF) delay
T
SL
: The SmartSlice bus communication cycle time
T
SL-CI
: The SmartSlice Communication Unit’s input data processing time
T
SL-CO
: The SmartSlice Communication Unit’s output data processing time
T
RM
: The entire PROFIBUS communication cycle
T
PLC
: The PLC's cycle time
T
RF
: The PLC's PROFIBUS Unit refresh time
Note
Refer to the
GRT1 Series SmartSlice I/O Units Operation Manual
for details
on Input Unit’s input delay times and Output Unit’s output delay times.
PROFIBUS
Communication Cycle
Time (T
RM
)
The PROFIBUS communication cycle time is the time from the completion of
a Slave's remote I/O communication processing until remote I/O communica-
tion with the same Slave are processed again. The communication cycle time
is used to calculate the maximum I/O response time.
The communication cycle time (T
RM
) is defined by the Bus parameter settings
for the PROFIBUS Master Unit (Refer to the
CS/CJ-series PROFIBUS DP
Master Units Operation Manual
).
Refresh Time (T
RF
)
The refresh time is the time required to exchange I/O data between the PLC's
CPU Unit and the PROFIBUS Master Unit. The PLC's cycle time is increased
when a Master Unit is mounted, as shown below.
Master Units for CS, CJ,
C200HX/HG/HE (-Z), and
C200HS PLCs
When a Master Unit is mounted to the PLC, the PLC's cycle time (I/O refresh-
ing) is increased by the amount shown in the following table.
Note
1.
The number of words refreshed is the total number of words in the I/O Area
allocated to the Slaves, including any unused words between the allocated
words. For example, if there are only two Input Slaves with station address-
es 1 and 5, the 5 input words for stations 1 through 5 would be refreshed
even though the input words for stations 2, 3, and 4 are unused.
PLC
PROFIBUS
Communications Unit
SmartSlice bus
Input Unit
Output Unit
T
OUT
T
SL
T
SL- CO
-
T
RM
T
PLC
T
RF
T
PLC
T
PLC
T
RF
T
RF
T
RM
T
SL-CI
T
SL
T
IN
PROFIBUS Master unit
I/O Refresh processing time
CS1/CJ1W-PRM21
0.7 + 0.001 × number of words (ms) (See note 1)
C200HW-PRM21
• For C200HX/HG/HE (-Z) PLCs:
1.72 + 0.022 × number of words (ms) (See note 1)
• For C200HS PLCs:
2.27 + 0.077 × number of words (ms) (See note 1)
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