Omron CVM1-CLK21 Data Link I/O Response Time, Data Exchange Timing, Being issued, Bytes

Data Link I/O Response Time				Section 8-3
	The number of bytes in each message differs according to the instruction
	being issued.
	Instruction	When sent		When received
	SEND	Number of words to be sent ⋅ 2		14
		+ 18
	RECV	18		Number of words to be
				received ⋅ 2 + 14
	CMND	Number of bytes in command		Number of bytes in response
		data + 10		data
Calculation Example
	Communications conditions are as follows:
	Transmission medium:		Twisted-pair cables
	Baud rate:		2 Mbps
	Network parameters:		Defaults
	Max node address:		32
	Polled nodes per comm cycle:		4
	Event-frames per comm cycle:		35
	Network configuration:		8 nodes
	Nodes that send messages:		2 nodes
	Bytes in all messages sent:		2,012 ⋅	2 bytes

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 ⋅ 2 + 4 ⋅ 4,024 + 2,290 = 22,306 (∝s)

≅22 (ms)

8-3 Data Link I/O Response Time

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.

8-3-1 Data Exchange Timing

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.

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