File service on PLC network

[Bruceh]

I am in the process of planning to network four T100MD+ PLC's that are running product test stations.
The aim is to have the PLC's report their test results back to the intranet and have results saved in a file on the network.

If I connect the PLC's together on a RS485 connection and then use a X-Server module to connect to the intranet  then the PLC's can be accessed by TLServer on the intranet - so far, so good.

The next bit I'm unsure of.
To collect information from the PLC"s I think there are two options that I'm aware of:

1 - Use Tri-Excel link to query the PLC's and read variables from them. However I only want the information to be collected once the PLC has completed a test, Tri-Excel link only appears to collect information on a timed basis (eg every XX seconds). How do I make the information collection conditional on completion of test? Would this condition have to be tested in Excel via a macro? eg collect info every 10 sec and look for a test complete flag, if flag is up then paste last data collected into spreadsheet, otherwise ignore

2 - Use  file service requests from the PLC to append data to a text file. This looks like a good solution but I am concerned that the manuals do not give an example of file services going out thru port #3 (RS485). Can I use file service requests on the RS485 network via the X-server to append files on the intranet?  

Or is there another way?
 
Regards

[support]

1) ExcelLink can only poll the internal variables at fixed internal according to its setup. So you are right that you can program the PLC to change a certain variable (serves as a flag) to signal that data are ready. An Excel macro can be written to check the flag continuously until it sees the signal, then copy the polled data into required spreadsheet location or data base. If there is no flag then the polled data are ignored.

2) File and Email service can't work properly via RS485 port. Especially since you have multiple PLC connected to the same RS485, there is going to be multiples messages from different PLC that collides and corrupt the data. Even on a one-to-one, File and Email service cannot work properly because of RS485 driver turnaround issue.

One possibility is to use a T100MD+ PLC as a master PLC and your four other PLCs as slave. The master can then polled the data, check for ready flag etc from all 4 slave PLCs into its internal DM area. This master PLC can then write the data to the PC hard disk using the remote File Service capability of the XServer to write to a remote TLServer.