Data Link I/O Response Time; Computer To Pc - Omron SYSMAC 3G8F7-CLK13-E Operation Manual

Data Link I/O Response Time

8-3

Data Link I/O Response Time

8-3-1

Computer to PC

User application
(ClkWriteDatalink)
PC at node #2
1,2,3...
(32 + 1.7)/32 × 100
≅ 105.3 (%)
The data links of the Controller Link Support Board require a slight time delay
from the time the data link area of one node is changed until this change is
reflected in the data link area at another node. This time delay is called the
data link I/O response time.
In the following diagram illustrating the maximum data link I/O response time,
a CS-series PC is used for the PC (#2) and the PC's cycle time is greater than
or equal to the communications cycle time.
Computer at node #1
Send processing (FinsGateway)
(*)
Late
1 cycle
Data link I/O response time
There are two points shown in the diagram above where processing is
delayed.
1. Data exchange occurs just after the computer at node #1 passes the token
that makes it the polling node, causing a delay of up to one communica-
tions cycle time before the data is transferred in data link processing.
2. The data transferred in data link processing arrives at the PC at node #2
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. (If the cycle time of the
PC at node #2 is longer than the communications cycle time, the delay
would be approximately two cycles.)
The maximum number of words that can be transferred in one data exchange
is 3,700 words for the CVM1 and CV-series PCs and 7,800 words for the CS-
series and CJ-series PCs.
Communications
cycle time
Data link transmissions
Output device
Section 8-3
I/O refresh
Data exchange
Output ON delay
133