CLI: Job Pending

[Instamed]

Hello!
First of all I would like to thank you for your good job Davide.

Well, i have some questions:

I have two clients connected with a s7 300. They are connected when inits app and never disconnect.
One client is in thread writing in loop values to a dw.
Other one is reading that's values and presenting.

Sometimes when reading in syncronous mode (ReadArea) i receive error messages of "CLI: Job Pending".
Why? i supose that these errors are present in async calls...

Also when i unplug ethernet cable or switching clp to OFF for testing errors connection, never reconnects...
How can i solve this?

Thanks

Release : 1.4
OS : Windows 8.1
CPU : x64
Wrapper : dot.net -> snap7.net.cs

[Davide Nardella]

Hi,
Snap7 library is object oriented all resources are inside the classes and there are no global vars.

Your error has not sense in a sync call.
Are you completely and absolutely sure that you are not mess with your classes ?

That said, the class itself (for optimization reasons) is not thread safe : accessing the same class contemporary from two different threads can lead your problem.

---

Snap7 client is a low-level driver, to detect and recover network errors you should insert your operations in a thread checking the TCP error:

A simply fast pascal code:

// While cycle inside the thread body, Terminated is a boolean which indicates that
// the thread must exit
while not Terminated do
begin

if not Client.Connected then
begin
repeat
sleep(500); // try to reconnect every 500 ms
until (Client.Connect=0) or Terminated;
end;

if not Terminated then
DoSomethingWithClient;

// Check if the low part of the error is a TCP error
if (Client.LastError and $0000FFFF)<>0 then
Client.Disconnect;

end;

You can look also to the S7partner c++ code which uses the same mechanism to automatically reconnect.