HannAri

Hi folks,

I am using Done and Error as condition to call the next Mudbus_master. After a while the communication stopped because one of the Modbus_masters got stuck on Busy. Does anyone know why this is happening? According to someone I talked to at the SIEMENS Support then this is not supposed to happen. The Blocked_Proc_Timeout is supposed to prevent this. This Blocked_Proc_Timeout is set default to 0.5 (I am guessing that is seconds.) How does this differ from the RESP_TO that you set in the Modbus_Comm_load? Because that is set default to 1000 (1s).

In attachment (Download from WeTransfer) is a project where I am shifting between two devises. In NW3 I added a condition that if MB_master is busy for more 1s then it goes to next device. This seems to work but I don’t want to have it if there is a better way.

Perhaps someone can send me a project they have done with multiple master block that works.

Attachment: http://we.tl/drp46an9W0

I had faced a similar problem ( Busy bit gets stuck ).
To solve this problem, I added  a Timeout timer in case neither Error nor Done is received for a certain time ( Say 2 Sec ).

The TImer output is used reset and re-trigger communications.

Hope this helps
Cheers
Navnag

HannAri

That is basically what i am doing except I just continue reading from next devise if busy is on for too long. Just like I said before I was told that this wasn’t supposed to happen. How do you reset and re-trigger communication?

 That is exactly what I did

HannAri

Hi Navnag. 

How do you go by reseting and re-triggering the communication?

Reset ( Disconnect )  By -> Making REQ -> 0 and DISCONNECT as -> 1

Time Delay after Busy = 0

Re-trigger By -> DIsconnect -> 0 and REQ -> 1

Tip : If you get continuous Busy Bit , Try to increase your polling cycle time