Omron CS1W-SLK11-21 - 06-2004 Manual page 123

PLC Network Instructions
Note
Example
RECV(98) Instruction
Maximum Delay Time
Note
RECV (98) executed
Transmission delay (command)
Reception processing (command)
106
Transmission Delay
Number of words transferred × 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 sending 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
Destination node CPU execution processing: Non-synchronous
Number of words:
Communications:
Data link:
Delay cause
Link servicing interval (source node)
Link service processing (source node)
Communications cycle time
Transmission processing
Transmission delay
Reception processing
Link servicing interval (destination node)
Link service processing (destination node)
Max. transmission delay
The data flow which will yield the maximum transfer interval from the time the
RECV(98) instruction is executed by the user program to the time the SYS-
MAC LINK Unit stores the data in the local Unit's memory area is described
below.
Be sure to take into account the time required for data links and program exe-
cution, which are not included in the following example.
Link service processing (source node)
Transmission processing (command)
Maximum transmission delay
32
32
256
coaxial cable
halted
Data stored
Reception processing (response)
Transmission delay (response)
Transmission processing (response)
Link service interval (destination mode)
Link service processing (destination node)
Section 6-2
Maximum delay (ms)
PLC cycle time
1 ms
32 × 0.01 + 32 × 0.075 + 4 × 0.75 +
1.322 = 7.042 ms
256 × 0.0045 + 4 = 5.152 ms
256 × 0.008 + 0.204 = 2.252 ms
256 × 0.0045 + 4 = 5.152 ms
CPU Unit cycle time
1 ms
CPU Unit cycle time (source
node) + CPU Unit cycle time
(destination node) + 21.598 ms
Link service processing (source node)
Link service interval (source node)
Communications cycle