DShailendra

I have HMI TP177B touch communicating with S7-400 PLC via MPI. I want to show connection status on the screen. So I made one tag in HMI and connect it with "always ON" bit M1.0 of PLC. then I used this HMI bit to display color of a text box "PLC connection". If tag =1 green, tag=0 red

After starting HMI screentext box shows red color. When I connect MPI connector to PLC, it becomes green. thus the tag is working ok.

Butif I remove MPI connector from PLC, the color does not change to red. If I restart HMI, it again shows red color Why the tag value does not update?

please somebody guide me what mistake I am doing. The tag type I defined in HMI is cyclic on

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Import of a Technical Question of the User DShailendra

DShailendra

I have HMI TP177B touch communicating with S7-400 PLC via MPI. I want to show connection status on the screen. So I made one tag in HMI and connect it with "always ON" bit M1.0 of PLC. then I used this HMI bit to display color of a text box "PLC connection". If tag =1 green, tag=0 red

After starting HMI screentext box shows red color. When I connect MPI connector to PLC, it becomes green. thus the tag is working ok.

Butif I remove MPI connector from PLC, the color does not change to red. If I restart HMI, it again shows red color Why the tag value does not update?

please somebody guide me what mistake I am doing. The tag type I defined in HMI is cyclic on

Hi DShailendra,,

In your OP177B there is a Communication-Connection there is a tab called Area Pointer,
under Area Pointer select "Coordination" .There are 3 bits in the "Coordination" one of them is called Life Bit which flashes every second.
You can check the bit in the PLC and if it is not flashing more than 2-3 seconds you can generate an alarm.
This example is made for Protool but is the same for WinCC Flexible:
Monitoring the connection between a panel and the control