Omron CS1W-CLK21-V1, CVM1-CLK21, CS1W-RPT01, CJ1W-CLK21-V1 Error Detection Program Example

Checking Data Link StatusSection 5-4

5-4-5 Error Detection Program Example

Local node	Node 1	Node 1
Data Link	Data Link Participating Flag	Communications Error Flag
Participation Flag			Node 1
			Error output
	Node 2
		Node 2
	Data Link Participating Flag	Communications Error Flag
			Node 2
			Error output
	Node 32
		Node 32
	Data Link Participating Flag	Communications Error Flag

Node 32

Error output

When the source node's data link is participating, the AND condition of the data link status for each node can be taken using the Data Link Participation Flag and the Communications Error Flag, and the error output.

The following example shows an error output program for cases where the local node data link stops.

The local node's Communications Error Flag (in the data link status area) will be turned ON if the local node is isolated from the network while the data link is active. In this case, the data link remains active, so the node's Data Link Participation Flag will remain ON even though the node is isolated from the network.

Local node

Data Link Participation Flag

DIFD 10000

Local node

Communications Error Flag

DIFD 10000

10000

Local node Error output

Release Flag

Local node Error output

5-4-6 Programming Examples for Processing Data when Errors Occur

If a communications error occurs in a data link and valid data link data cannot be received, the previous data is stored in the data link area. To stop process- ing using the data link data when an error occurs, refer to the following pro- gram example.

Processing Data Only when Data Links Are Operating Normally

Perform processing only when the data links are operating normally by includ- ing an AND condition for the Data Link Normal Operation Flag in the part of the program that handles data link data for each node. This is an example of programming locks in the appropriate places.

Additional part

Normal Operation

Flag

Normal Operation

Flag

The parts of the ladder program that use the data link area for the relevant node are processed only when the corresponding Normal Operation Flag is ON.

“Data Link Normal Operating Flags” can be created using the programming described in 5-4-5 Error Detection Program Example.

162