Omron CJ1W-DRM21, CS1W-DRM21 operation manual System Startup Time, Master Function, Tions start up

Remote I/O Communications Characteristics Section 8-1

Note Although in the above diagram the Slaves are separated into two groups for convenience, the actual physical positions in the Network are irrelevant.

Next, we can refer to 8-1-1 Communications Cycle Time and Refresh Time and calculate the communications cycle time for each group as if they were separate Networks.

Group A

Master A

Slave A Slave B Slave C

Group A communications cycle time: TRM-A

Group B

Master B

Slave D Slave E Slave F

Group A communications cycle time: TRM-B

		In Networks with two Masters, the communications cycle time for the entire
		Network will be the sum of the communications cycle times for the groups.
		TRM = TRM-A + TRM-B
		Although this example shows only two Masters in the Network, the total com-
		munications cycle time for any Network can be calculated by dividing it into
		groups and adding the communications cycle times of all groups.
8-1-4	System Startup Time
Master Function
		This section describes the system startup time for a network operating with
		the scan list enabled. The system startup time is the delay from the time that
		the DeviceNet Unit (master) is turned ON until remote I/O communications
		begin. Here, we assume that the scan list is enabled and that remote I/O com-
		munications are set to start automatically at startup.
		The following table shows the system startup times for two cases. In the first
		case, the DeviceNet Unit starts up just after all of the Slaves’ power supplies
		are turned ON. In the second case, the DeviceNet Unit is restarted while com-
		munications are in progress.
		Case	Slave’s indicator status	System
				startup time
		The Master is	The NS indicator is OFF or flashing green.	5 seconds
		started just after
		Slave startup.
		Just the Master is	The NS indicator is flashes red while the Mas-	7 seconds
		restarted.	ter is OFF.
		Just the Slaves are	---	9 seconds
		restarted.
Program Example
		As shown in the preceding table, it takes time for DeviceNet communications
		to start up. This programming uses flags in the Master status area to prevents
		the Slaves’ I/O processing from being performed until remote I/O communica-
		tions start up.

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