Yaskawa DSD 406 - Manual (Page 106)

Glossary
102 Glossary
3/21/96
same time frame. MicroTrac DSD is provided with four timed scans and one
background scan. Each PAC task programmed in a timed scan will execute once
in that time frame. The background scan executes each PAC task once in
whatever time is left over from the timed scans and then starts over executing
each task again.
SCDU – Standard Control/Display Unit. The 4-1/2 digit numeric display, 4
push buttons (keypad) and multi-color LED on the drive. It allows viewing and
setting of variables.
Selected menu item – The menu item number in the RDU’s menu that is being
displayed.
Severe fault – An abnormal condition whose severity requires immediate action
by the microprocessor sensing the error. An example of a severe error is an IST
condition sensed by the PCU. In this case, the PCU disconnects the load; it does
not wait for the PAC program to command load disconnect. (Also see FAULT
definition.)
Speed Command – The desired speed setpoint prior to local PAC task
modification such as linear accel/decel control, draw modification, trim
modification, etc. (Also see SPEED REFERENCE definition.)
Speed Reference – The speed reference signal after all PAC task modification
such as linear accel/decel control, draw modification, trim modification, etc.
That is, the instantaneous value of the reference which is applied to the speed
regulator. (Also see SPEED COMMAND definition.)
Standard fault – A fault (or error) which is independent of a particular PAC
design. These conditions are associated with the operation of the DCU
microprocessor or the PCU or the LAN handler. (See FAULT or ERROR
definition.)
Subchannel – The PAC language defines a particular input or output by use of a
Node, a Channel, and a Subchannel. The Subchannel refers to a specific input or
output of a given Node and Channel.
The third level of addressing which further defines the location of information
external to the PAC program environment; the first level is the Node number
(see NODE definition) and the second level is the Channel number (see
CHANNEL definition). To access information requires specifying all levels of
addressing defined for that piece of information. For example, Node 251,
Channel 4, Subchannel 0 refers to the Local Digital I/O PCB connected to
connector J1 (assigned Node 251), Thumbwheel switch inputs (assigned as