Omron CJ1W-CLK21-V1, CVM1-CLK21, CS1W-RPT01, C200HW-CLK21, CQM1H-CLK21, CS1W-CLK21-V1 261

Data Link I/O Response Time Section 8-3

Case 4

The following diagram illustrates the data flow that will produce the maximum data link I/O response time when the cycle time of the PLC at node #1 < the communications cycle time and the cycle time of the PLC at node #7 < the communications cycle time.

Input

	Input device	I/O refresh
		Data exchange
Input ON delay

X	(1)		1 cycle
		Program		PLC at node #1
		X	(2)
		A		Controller Link Unit
				transmission processing
				Data link transmission
		Communications		Controller Link Unit
		cycle time		transmission processing
				(3)
			Previous communications
			cycle data	X
		PLC at node #7		Program
				1 cycle
				Output device
				Output ON
				delay
		Data link I/O response time		Output

There are three points shown in the diagram above where processing is delayed, increasing the data link I/O response time.

1,2,3... 1. The input arrives in the PLC just after I/O refreshing, causing a delay of up to one cycle before the input is read into the PLC.

2.At point A data from the previous data exchange is still being transferred, so the new data cannot be exchanged, causing a delay of up to one com- munications cycle time. Furthermore, the data exchange then occurs just after the PLC at node #1 passes the token that makes it the polling node, causing another delay of up to one communications cycle time before the data is transferred in data link processing.

3.The data transferred in data link processing arrives at the PLC at node #7 while data exchange is taking place, so the data will not be read into the PLC until the next data exchange, causing a delay of up to 1 to 2 cycle.

The maximum number of words that can be exchanged in a single data ex- change is approx. 7,800 words for CS/CJ-series PLCs, approx. 3,700 words for CVM1 and CV-series PLCs, approx. 4,000 for C200HX/HG/HE PLCs, and approx. 1,200 words for CQM1H-series PLCs.

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