GE Mark VIe System Manual page 55

1.7.10 Forced Variables
The controller has a feature called Forced Variables. This allows the maintenance technician using application software to set
analog or logical variables to forced values. Variables remain at the forced value until unforced. Both compute and input
processing respect forcing. Any applied forcing is preserved through power down or restart of the controller.
Warning
1.7.11 Peer I/O
In addition to the data from the I/O modules, there is a class of data coming from other controllers in other cabinets connected
through the UDH network. For integrated systems, this network provides a data path between multiple turbine controllers and
possibly the controls for the generator, the exciter, or the HRSG/boiler.
Selected signals from the controller database can be mapped into pages of peer outputs that are broadcast periodically on the
UDH I/O to peer controllers. For TMR systems, the UDH communicator performs this action using the data from its internal
database. In the event of a redundant UDH network failure, the controller will request data over the remaining network, the
IONet.
Control System Overview
Logic Forcing is for offline software checkout and troubleshooting and should only be
used in conjunction with proper lockout/tag out procedures. Forcing of protective
functions is never permissible for an operating unit.
Public Information
GEH-6721_Vol_I_BP System Guide 55