Dawn CONTROL-1500A Manual page 56

CONTROL-1500A Single Axis Antenna Controller
POS
FST/SLO THRSH:80
0-99 CNTS
The Retry Attempts CONFIG mode item sets the maximum number of attempts which will be
made to hit a target position (within 'Max Position Error' counts - described below) during an
automatic move initiated from AUTO mode.
POS
RETRY ATTEMPTS:3
2–5
The Fst Deadbnd and Slo Deadbnd CONFIG mode items are used for the anti-reversal
system. To understand the purpose of these parameters, it is necessary to consider how
position counts are accumulated. The feedback from the position sensor is pulses. When a
pulse is received, the controller checks to see which way the antenna was last commanded to
move. If the antenna is moving, or last moved, CCW, the position count is decremented. If the
antenna is moving, or last moved, CW, the position count is incremented.
In MANUAL mode, the user can jog the antenna. If the AZ CW arrow key is depressed, the
antenna will move up. If the user suddenly depresses the AZ CCW arrow key and the antenna
drive signals were instantaneously reversed, the antenna continues to move CW for some
small period of time, then the antenna reverses direction and starts to move CCW. This can
cause position count errors. When the antenna drive signals are configured for CCW
movement but the antenna is still moving CW, pulses which are received would cause the
position count to decrement when the count should really be incremented because the
antenna is really still moving CW.
The anti-reversal system keeps the antenna from rapidly changing direction. If the antenna
has been moving in a given direction, the 'Deadbnd CONFIG mode items specify the amount
of time (in milliseconds) that the system will wait before asserting the antenna drive lines to
move the antenna in the opposite direction. There are 2 different Deadbnd values specified -
there are unique fast and slow speed values. If the antenna has been moving fast, the Fst
Deadbnd parameters specify the wait interval; if the antenna has been moving slow, the Slo
Deadbnd parameters specify the wait interval. Both Deadbnd values are given in milliseconds.
POS
FST DEADBND:2000
175-5000 MS
POS
SLO DEADBND:_800
175-5000 MS
The values assigned to the Fst Deadbnd and Slo Deadbnd variables can affect other systems
on the controller not related to the anti-reversal system. These features are explained in
Chapter 7 - Operational Troubleshooting Tips. For normal operation these features should be
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POL SS
CFG
MODE
POL SS
CFG
MODE
POL SS
CFG
MODE
POL SS
CFG
MODE
Chapter 4 Modes Function Description
49