Data Link I/O Response Time; Data Exchange Timing - Omron C200HW-CLK21 Operation Manual

Data Link I/O Response Time

Calculation Example
8-3 Data Link I/O Response Time
8-3-1

Data Exchange Timing

The number of bytes in each message differs according to the instruction
being issued.
Instruction
SEND Number of words to be sent 2
+ 18
RECV 18
CMND Number of bytes in command
data + 10
Communications conditions are as follows:
Transmission medium:
Baud rate:
Network parameters:
Max node address:
Polled nodes per comm cycle:
Event-frames per comm cycle:
Network configuration:
Nodes that send messages:
Bytes in all messages sent:
In this example, B to E in the equation have the following values.
B: 4
C: 8
D: 2
E: 4,024
The communications cycle time is thus as follows:
600 4 + 110 8 + 320
22 (ms)
When accurate communications timing is required, you need to understand
data exchange timing and the time required for data transmission and recep-
tion via data links. Use the information described in this section as reference
information for system construction.
This section describes data exchange timing for data links between the Con-
troller Link Unit and the PLC's CPU Unit. Data exchange is executed as inter-
rupt processing during CPU Bus Unit or Programming Device/Host Link
servicing performed by the CPU Unit. This interrupt processing is executed
each time data exchange between the local node and each node connected
via a data link is completed.
Data exchange timing differs depending on the CPU Unit model and the CPU
Unit the Execute Process (asynchronous or synchronous) specified in PLC
Setup, as described below.
When sent
14
Number of words to be
received
Number of bytes in response
data
Twisted-pair cables
2 Mbps
Defaults
32
4
35
8 nodes
2 nodes
2,012 2 bytes
2 + 4 4,024 + 2,290 = 22,306 ( s)
Section 8-3
When received
2 + 14
253