beautypg.com

Omron CQM1H-CLK21 User Manual

Page 287

background image

264

Data Link I/O Response Time

Section 8-3

2.

Data exchange occurs just after the PLC at node #1 passes the token that
makes it the polling node, causing a delay of up to one communications cy-
cle time before the data is transferred in data link processing.

3.

At node #7, data from the previous data exchange is still being transferred,
causing a delay of up to one cycle before the input is read into the PLC.

4.

The data transferred in data link processing arrives at the PLC at node #7
after data exchange, so the data will not be read into the PLC until the next
data exchange, causing a delay of up to one peripheral servicing interval.

Up to 3,700 words can be transferred in a single data exchange, so a delay
of another peripheral servicing interval will occur if more than 3,700 words
are being transferred.

5.

The data is received after the PLC at node #7 has executed the instruction,
causing a delay of up to one cycle time.

Assume that the peripheral servicing interval of the PLCs at nodes #1 and #7
is 10 ms. The equation for maximum data link I/O response time is as follows:

Note If the total number of data link words is greater than the maximum number of

words that can be exchanged per data exchange, the maximum data link I/O
response time will be cycle time of PLC at node #7

×

3.

Noise may increase I/O delays.

Minimum Response Time

Input ON delay

1.5 ms

Cycle time of PLC at node #1

×

2

15 ms

×

2

Peripheral servicing interval of PLC at
node #1

10 ms

Communications cycle time

×

3

9.9 ms

×

3

Peripheral servicing interval of PLC at
node #7

×

2

10 ms

×

2

PLC cycle time at node #7

×

2 (See note.) 20 ms

×

2 (See note.)

Output ON delay

15 ms

Total (data link I/O response time)

146.2 ms

Input

Input device

Input ON delay

1 cycle

I/O refresh

PLC at node #1

PLC at node #7

Peripheral servicing interval

Peripheral servicing interval

Output device

Output
ON delay

Data link I/O response time

Program

Program

Data link transmission

Data processing time

Data processing time

This manual is related to the following products: