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8-1
Section
Remote I/O Communications Characteristics
153
Maximum I/O Response Time
The maximum I/O response time occurs with the I/O timing shown in the
following diagram.
Instruction execu-
tion cycle time
Peripheral serv-
icing cycle time
Peripheral servic-
ing cycle time
PROFIBUS-DP Master Unit
PRT1-COM
Communication Unit
PROFIBUS-DP I/O response time
Input Unit
Output Unit
PC
T
RM
T
RM
T
IN
:
Input I/O Unit ON (OFF) delay time
T
OUT
: Output I/O Unit ON (OFF) delay time
T
CYCIF
: I/O Unit interface cycle time (see
8-1-3 I/O Unit Interface Cycle Time
)
T
RM
:
PROFIBUS-DP cycle time for the whole network
The maximum I/O response time (T
MAX
) is the total of the following terms:
T
MAX
= T
IN
+ T
CYCIF
+ (PROFIBUS-DP I/O response time) + T
CYCIF
+ T
OUT
Note
For details on the Input I/O Unit input delay time and the Output I/O Unit output
delay time, refer to information on the I/O Units in
6-1 Common Specifications for
Basic I/O Units.
Note
Refer to the PC’s Operation Manual for details on the PC’s cycle time.
8-1-2 PROFIBUS-DP Cycle Time
The PROFIBUS-DP cycle time is the time from the completion of a Slave’s
remote I/O communications processing until remote I/O communications with
the same Slave are processed again. The PROFIBUS-DP cycle time is used to
calculate the maximum I/O response time.
The PROFIBUS-DP cycle time depends on the number of masters and total
number of slaves in the network. For calculating the PROFIBUS-DP cycle time
refer to PROFIBUS-DP Master Unit Operation Manual (W349).
The time required to exchange data between the master unit and the PLC CPU
can also be found in this manual.
8-1-3 I/O Unit Interface Cycle Time
The I/O Unit interface cycle time is the time interval between the I/O processing
of I/O Units in a MULTIPLE I/O TERMINAL and the next I/O processing for those
I/O Units.
If there is not a Special I/O Unit, the I/O Unit interface cycle time is:
T
RT-IF
= 1.5 [ms]
More frames are required with a Special I/O Unit. There will be one additional
special I/O data frame per Special I/O Unit and one additional frame for checking
the status of all the Special I/O Units. Therefore, the I/O Unit interface cycle time
with a Special I/O Unit can be calculated using the following formula:
T
CYCIF
= 1.5
×
(MOD + N + 1) [ms]
MOD: Number of I/O data frames
If there is no basic I/O Unit:
MOD = 0
If there are basic I/O Units:
MOD = 1
PROFIBUS-DP Cycle
Time
Without a Special I/O Unit
With a Special I/O Unit
Содержание PRT1-COM
Страница 1: ...Cat No W900 E2 1 PROFIBUS DP MULTIPLE I O TERMINAL PRT1 COM GT1 Series ...
Страница 2: ...PRT1 COM GT1 Series PROFIBUS DP MULTIPLE I O TERMINAL Operation Manual Produced December 1999 ...
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Страница 187: ...Cat No W900 E2 1 Note Specifications subject to change without notice December 1999 Authorized Distributor ...