SCADA_Dude
Member
Problem:
I have a AB SLC 5/05 (L551 Series C FRN 11) which is erroring on MSG blocks (Error D1), which is Already at max number of open connections.
Details:
1. This PLC polls 14 remote PLC's, each with a Read & write MSG block. (14 connections or 28 connections depending on how you count them - see below)
2. Two HMI PC's with AB driver (4 connections)
3. Occasional RSlinx connection for going online for programming. With this connection open, two of the remotes MSG give the D1 error. With this connection closed, only one remote gives the error. (2 connections)
My Question:
I called AB tech support and they referred me to knowledge base 17469. According to this document, L551 w/ FRN 11 has 32 available connections. In the SLC instruction set manual it states a read and a write to the same address uses the same connection. By this count I should not be running out of connections (14 + 6 = 20). There is a note in this knowledge base that states "Note: If 5/05 'A' sends a MSG to 5/05 'B', 'A' uses one outgoing connection and 'B' uses one incoming connection. All subsequent MSGs sent by 'A' to 'B' use this same connection, as long as the "Inactivity Timer" in 'A' has not expired." If Im not conserving connections in this manner, then that explains my connection problem (14x2 + 6 = 34)
What is meant by Inactivity timer? The AB guy didnt know what it meant. Do I have to issue the Read and Write simultaneously? I have them spaced out by a few seconds in my polling loop right now.
I really hope someone has run into this problem before, because I dont want to upgrade to a L552 if at all possible. All this dumb PLC does is poll remotes, that would be a waste of money if you ask me.
Any input is greatly appreciated.
I have a AB SLC 5/05 (L551 Series C FRN 11) which is erroring on MSG blocks (Error D1), which is Already at max number of open connections.
Details:
1. This PLC polls 14 remote PLC's, each with a Read & write MSG block. (14 connections or 28 connections depending on how you count them - see below)
2. Two HMI PC's with AB driver (4 connections)
3. Occasional RSlinx connection for going online for programming. With this connection open, two of the remotes MSG give the D1 error. With this connection closed, only one remote gives the error. (2 connections)
My Question:
I called AB tech support and they referred me to knowledge base 17469. According to this document, L551 w/ FRN 11 has 32 available connections. In the SLC instruction set manual it states a read and a write to the same address uses the same connection. By this count I should not be running out of connections (14 + 6 = 20). There is a note in this knowledge base that states "Note: If 5/05 'A' sends a MSG to 5/05 'B', 'A' uses one outgoing connection and 'B' uses one incoming connection. All subsequent MSGs sent by 'A' to 'B' use this same connection, as long as the "Inactivity Timer" in 'A' has not expired." If Im not conserving connections in this manner, then that explains my connection problem (14x2 + 6 = 34)
What is meant by Inactivity timer? The AB guy didnt know what it meant. Do I have to issue the Read and Write simultaneously? I have them spaced out by a few seconds in my polling loop right now.
I really hope someone has run into this problem before, because I dont want to upgrade to a L552 if at all possible. All this dumb PLC does is poll remotes, that would be a waste of money if you ask me.
Any input is greatly appreciated.