Checking Data Link Status

Section 5-4

Processing Data Only when Operation Is Normal Using the IL-ILC and JMP-JME Instructions

Perform processing only when operation is normal by creating a program based on program blocks that process data for each node with the IL-ILC and JMP-JME programs.

Node A Data Link Normal Operation Flag

Node B Data Link Normal Operation Flag

Node C Data Link Normal Operation Flag

IL

Node A data processing

ILC

IL

Node B data processing

ILC

IL

Node C data processing

ILC

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

Writing 0000 in the Data Link Area when Errors Occur

When data links are not operating normally, write 0000 to the data link area of the node with the error to stop other data being received.

As an example, the following example shows how to write 0000 in the data link area of node 2 (D00100 to D00120) using the BSET (block set) instruction when an error occurs at node 2.

Data Link Example: Communications Error at Node 2

Node 1

 

 

 

Node 2

Node 1

 

 

 

Node 1

 

 

 

 

 

Node 2

X

 

 

Node 2

 

 

 

 

 

 

Node 62

Node 1

Node 2

Node 62

Node 62

Node 62

Example of Programming for Node 1 to Handle Communications Errors at Node 2

Node 2 Data Link

Normal Operation Flag

BSET

# 0 0 0 0

D00100

D00120

0000 is written continuously in node 2's area (D00100 to D00120) until node 2's flag turns ON.

Insert the above programming at the start of the program.

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

Note 1. If an error occurs and 0000 is written to the Data Link Area occurs for an unstable transmission path (i.e., one that repeatedly alternates between communications errors and normal operation), the normal data will be fre-

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Omron CVM1-CLK21 Writing 0000 in the Data Link Area when Errors Occur, Data Link Example Communications Error at Node