Omron CS1W-SLK11-21 - 06-2004 Manual page 124

PLC Network Instructions
Note
Example
Max. transmission delay = Link servicing interval (source node) + Transmis-
sion processing (command) + Communications cycle + Transmission delay
(command) + Reception processing (command) + Link servicing interval (des-
tination node) + LINK service processing (destination node) + Transmission
processing (response) + Communications cycle + (transmission delay
(response) + Reception processing (response) + Link servicing interval
(source node) + LINK service processing (source node).
Link Servicing Interval (Source and Destination Nodes)
Links are serviced once per PLC execution cycle. Refer to the CS-series PLC
Operation Manual for details.
Link Service Processing (Source and Destination Nodes)
Link service processing is the same as the PLC's peripheral servicing and is
approximately 1 ms for SYSMAC LINK Units.
Transmission and Reception Processing
Commands: 2 ms
Responses: Number of words transferred x 0.0045 ms + 4 ms
Communications Cycle Time
Max. node address × 0.01 ms + No. of nodes × 0.075 ms + No.
Coaxial:
of polled units × 0.75 ms + 1.322 ms
Optical: Max. node address × 0.01 ms + No. of nodes × 0.133 ms + No. of
polled units × 0.75 ms + 1.322 ms
Transmission Delay
Commands: 0.204 ms
Responses: Number of words transferred x 0.008 ms + 0.204 ms
The I/O response time can increase due to noise or restrictions on the number
of frames that can be transmitted while the data link is operating.
In this example, the maximum transmission delay is calculated for an instruc-
tion receiving 256 words of data in a system with 32 nodes. Network specifics
are detailed below:
Max. node address:
Number of nodes:
Number of polled units: 4
Number of words:
Communications:
Data link:
Delay cause
LINK Unit servicing (source node)
LINK service processing (source node)
Transmission processing (command)
Communications cycle
Transmission delay (command)
Reception processing (command)
Link servicing interval (destination node)
Link service processing (destination node)
Transmission processing (response)
Transmission delay (response)
32
32
256
coaxial cable
halted
Maximum delay (ms)
PLC cycle time
1 ms
2 ms
32 × 0.01 + 32 × 0.075 + 4 × 0.75 +
1.322 = 7.042 ms
0.204 ms
2 ms
CPU Unit cycle time
1 ms
256 × 0.0045 + 4 = 5.152 ms
256 × 0.008 + 0.204 = 2.252 ms
Section 6-2
107