Performance; Plc Cycle Time - Omron C200HW-CORT21-V1 Operation Manual

Performance

2-3

Performance

2-3-1 PLC cycle time

PLC cycle time
I/O Refresh Time
Calculation
The overall performance of the C200HW-CORT21-V1 depends on the
performance of the host PLC interface and on the performance of the
CAN(open) interface. In the next two sub-sections, these two factors will be
described first. After that, the overall performance is described.
The host PLC's cycle time mainly depends on the size of the PLC program
and the I/O refresh times of all I/O Units connected to its I/O backplane(s).
The size of the PLC program is application specific. Apart from optimising the
PLC program, the program execution time can only be decreased by using a
faster CPU Unit.
The total I/O refresh time depends on the number and types of Units that are
mounted on the backplane(s). Not all Units refresh the same amount of data.
The I/O refresh time of the C200HW-CORT21-V1 depends on the number
and type of data objects that have been mapped, and whether user defined
CAN messages need to be received. Refer to section 4-2-3 for details about
mapping application objects on PLC memory locations and refer to section 5-
8 for receiving user defined CAN messages.
Using the default mapping mode (eight 8-bit objects allocated to the Special
I/O unit's IR area), the I/O refresh time of the C200HW-CORT21-V1 is:
t = 0.85 ms
IORF, def
When additional application objects are mapped using the Unit settings, the
I/O refresh time can be calculated with the following formula:
t = 0.85 + 0.45 x n a +
IORF
0.01 x n 8 + 0.02 x n 16 + 0.04 x n 32 + 0.08 x n 64 [ms]
where n a = number of data areas (0 ~ 6)
The C200HW-CORT21-V1 provides up to:
- 3 input data areas (8-bit, 16-bit, and 32/64-bit) and
- 3 output data areas (8-bit, 16-bit, and 32/64-bit).
An area is counted when the number of objects in that area is
greater than 0.
n 8 = number of 8-bit input and output objects (0 ~ 200)
n 16 = number of 16-bit input and output objects (0 ~ 200)
n 32 = number of 32-bit input and output objects (0 ~ 100)
n 64 = number of 64-bit input and output objects (0 ~ 50)
The total size of the input and output objects is limited to 100 words in and
100 words out.
When user defined CAN messages are received, the following time must be
added to the I/O refresh time:
t = 0.45 + 0.12 x n m
IORF,msg
where
n m = number of received CAN messages (1 ~ 15)
The maximum IO refresh time is therefore:
t = 0.85 + (0.45 * 6) + (0.02 * 200) + 0.45 + (0.12 * 15) = 9.8 ms.
IORF,max
Section 2-3
25