Simple Communications Watchdog for MW100

1. Simple Communications Watchdog for MW100 • Principle is to read seconds clock from other units and look for user-defined period of no-change from scan to scan • When seconds clock does not change for a number of scans then trigger alarm. • Can be repeated for multiple units.

2. A1  Logic to check if value in communication channel 1 is equal to it’s value from the prior scan (located in A2). If so then at increments A1’s value by value of math constant K1 (1) else if not equal (good communications) it is reset to K2 (0). A2  Value of communication channel 1 A3  Check to see if A1 exceeds threshold of K3 (30). This is how many seconds that we will let communications fail before setting an alarm. You can modify K3.

3. K1  Increment per scan K2  Reset count to 0 when good comms K3  Allowed count before alarm on bad comms

4. A003  Alarm on math channel A003 where if logical value is equal to or exceeds 1 then triggers appropriate relay.

5. Modbus Ethernet communications is enabled with a scan time of 1 second.

6. Enter IP Addresses of other units you wish to watchdog communications.

7. Read seconds register from other device(s) into free communications channel(s).

8. Set one measurement interval to 1 second.

9. Ensure math is scanning at same 1 interval (1 sec) as set under measurement settings.

10. Activation • Start Measurement • Start Math • A1 should increment if communications is lost. • A3 will trigger if A1 increments beyond value set in K3. • A1 will reset to 0 if communications is restored.