Omron SYSMAC LINK C1000H-SLK21-V1 System Manual page 99

NETWORK READ/WRITE Instructions
Example
RECV(98) Instruction
Maximum Delay Time
RECV(98) executed
Reception processing
(command)
In this example, the maximum transmission delay is calculated for an instruction
sending 256 words of data in a system with 32 nodes. Network specifics are
detailed below:
Max. node number:
Number of nodes:
Number of polled units: 4
Number of words:
Communications:
Data link:
Delay cause
LINK Unit servicing
Transmission processing
Communications cycle time
Reception processing
The maximum transmission delay is thus:
(PC scan time × 2) + 23.698 ms.
The following indicates the data flow which will yield the maximum transfer inter-
val from the time the RECV(98) instruction is executed by the user program to
the time the SYSMAC LINK Unit stores the data in the local Unit's memory area.
Note Be sure to take into account the time required for data links and program execu-
tion, which are not included in the following example.
Max. transmission delay
Transmission processing
(command)
Max. transmission delay = LINK Unit servicing interval (source node) +
Transmission processing (command) + Communications cycle + Reception
processing (command) + LINK Unit servicing interval (destination node) +
Transmission processing (response) + Communications cycle + Reception
processing (response) + LINK Unit servicing interval (source node).
SYSMAC LINK Unit servicing is performed once per PC scan.
Delay cause
Transmission/reception
processing (command)
Transmission/reception
processing (response)
Communications
1
cycle time
32
32
256
coaxial cable
halted
Data stored
Reception processing
(response)
Transmission processing
(response)
5 ms
No. of words transferred × 0.013 ms + 5 ms
Max. node no. × 0.01 ms + no. of nodes × 0.075 ms
Coaxial
+ no. of polled units × 0.75 ms + 1.322 ms
Max. node no. × 0.01 ms + no. of nodes × 0.133 ms
Optical
+ no. of polled units × 0.75 ms + 1.322 ms
Section 6-2
Maximum delay (ms)
PC scan time
8.328 ms
7.042 ms
8.328 ms
SYSMAC LINK Unit servicing
(source node)
Communications cycle
SYSMAC LINK Unit servicing
(destination node)
Delay (ms)
85