Omron CVM1-CLK21, Operation Manual

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200
Data Link I/O Response Time Section 8-3
CVM1, CV-series, CS/CJ-series PCs Under Synchronous Operation or C200HX/HG/HE
and CQM1H-series PCs
Maximum I/O Response
Time The maximum data link I/O response time is calculated for four cases.
Case 1
The following diagram illustrates the data flow that will produce the maximum
data link I/O response time when the cycle time of the PC at nodes #1 and 7
are greater than the communications cycle time.
There are four points shown in the diagram above where processing is
delayed, increasing the data link I/O response time.
1,2,3... 1. The input arrives in the PC just after I/O refreshing, causing a delay of up
to one cycle before the input is read into the PC.
2. Data exchange occurs just after the PC 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 PC.
4. The data transferred in data link processing arrives at the PC at node #7
after data exchange, so the data will not be read into the PC until the next
data exchange, causing a delay of up to one cycle.
The maximum number of words that can be exchanged in a single data ex-
change is approx. 7,800 words for CS/CJ-series PCs, approx. 3,700 words
for CVM1 and CV-series PCs, approx. 4,000 for C200HX/HG/HE PCs, and
approx. 1,200 words for CQM1H-series PCs.
Input device
Program
Program
Input
Input ON delay
1 cycle
Output
Output device
Output ON delay
1 cycle
Communications
cycle time
Data link transmission
Controller Link Unit
transmission processing
PC at node #7
(1)
I/O refresh
Data exchange
Controller Link Unit
transmission processing
PC at node #1
Previous communica
tions cycle data
Data link I/O response time
X
X
X X
(2)
(3)
(4)
X