Hello Adam,

as former engineer of STS may I can help you.
This error means that the PC does communicate with the modeles eg. VAC, PFC
etc
First switch of the 24V power supply for the tool and turn back on after 20
sec to restart the modules.
Second restart the PC software.

If the problem occurs again the shut down the process software agian and
start the diagnostic program.
It may tell you which of the modules of the seriel loop does not  respond.

Best  regards
Mit freundlichen Grüßen

André Hiess,  Technologieberatung-Service-Schulung
Gmünder Str.4, 01279 Dresden,  Germany
phone: +49 (0)351 2523577
mobile: +49 (0)1632581847
mail to:  hiess1@aol.com