Trace function for S7?

Hello,

This is my first posting on this site. I have recently been using Siemens scout on a servo project, and have found the trace tool to be very useful. It has been mentioned to me that there is an add-on tool that allows signals to be traced in S7. I usually just use VAT tables, but a trace would be so much better. I have had a quick google but with no luck.

Does anyone know of such an add-on?

Thanks in advance for the feedback.

Can't you simply store the state away in a big array in a DB? I would use a circular queue for this.

However, if you have a spare motion controller laying around you may consider sending what you want to trace or trend to the motion controller where it can save the data and graph it. It has been done before. Use the motion controller to debug the PLC program.

If you just need a basic tracing function, then there are many HMI softwares and also some standalone software that can do it.
Here is one:
http://www.upstatesoft.com/index.php?option=com_content&view=article&id=43&Itemid=4&lang=en

If the tracing must be accurate to catch every single cycle, then there is this product from Deltalogic:
http://www.deltalogic.de/content/view/34/57/lang,en/
Notice that it works by downloading some blocks in the CPU in order to be able to log data in each cycle.

edit: As an example on the do-it-yourself apporach, I use WinCC Flexible RT, and I can quickly program a regular trend to trace data. If need to catch every cycle I can program logging in code (as Peter suggest) combined with visualising the trend in WinCC Flex RT.

Here's another do it yourself version that stores data in DBs for you to analyse after the event(s).

http://www.plctalk.net/qanda/showpost.php?p=338247&postcount=3

I use this one as a trace function

http://www.servicelab.co.uk/servicelab/servicelab.nsf/id/pa_home_e.html