Quoting from http://members.iinet.net.au/~ianw/primer.html
SCADA (supervisory control and data acquisition): An industrial measurement and control system consisting of a central host or master (usually called a master station, master terminal unit or MTU); one or more field data gathering and control units or remotes (usually called remote stations, remote terminal units, or RTU's); and a collection of standard and/or custom software used to monitor and control remotely located field data elements. Contemporary SCADA systems exhibit predominantly open-loop control characteristics and utilise predominantly long distance communications, although some elements of closed-loop control and/or short distance communications may also be present.
Tcl Applications used for SCADA:
2017: EPICS is a set of Open Source software tools, libraries and applications developed collaboratively and used worldwide to create distributed soft real-time control systems for scientific instruments such as a particle accelerators, telescopes and other large scientific experiments.
Older than this page but some may still find something useful here http://www.aps.anl.gov/epics/ The TCL connection is here http://www.aps.anl.gov/epics/extensions/tcl/ .
This looks like it is still being updated though https://github.com/auriocus/AsynCA
Tcl Success stories relating to SCADA:
to be determined...
Page added by escargo on 24 Dec 2002. I hope other people might know of specifics having to do with Tcl as a solution for SCADA, especially cross-platform.