RC4500 Antenna Controller Chapter 6 Support
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6.1.2 Motor Drive
Axis JAMMED error displayed. A jammed error indicates that the axis was commanded to move, but the
RC4500 did not sense any movement within several seconds. A jammed condition may indicate one of
several conditions:
The mount’s mechanical drive mechanism is physically jammed. Inspect the mount to determine if
some mechanical problem (slipped gears, etc) exists. Unusual conditions such as icing may also cause
the mount to jam.
The mount’s position is not being sensed correctly by the RC4500. After resetting the drive error, go
to MANUAL mode and attempt to jog the axis in question. If the axis does move, check to see if the axis’
displayed position is updating. If the RC4500 doesn’t sense movement, it will declare a jam even though
the axis is moving.
The AIU’s motor drive is failing to output the required voltage to move the axis. Can the axis be
driven manually from a local control panel at the AIU? If not, check the limit switch circuit as shown in
Chapter 2 and refer to schematics provided with the AIU.
6.1.3 Automatic Movements
The mount begins an automatic movement but generates an “axis jammed” error. All automatic
movements move to a “target” location. If far enough away from the target, the move will initially be done
in the FAST speed for the axis and then switch to SLOW when close to the target. If the SLOW speed
has been set too low, the axis may jam. Attempt to move the axis in SLOW speed from the MANAUL
mode to duplicate the situation. If SLOW speed seems to be the problem, adjust the drive voltage up as
discussed in section 4.2.2.
6.1.4 GPS
The interface between the RC4500 and the optional GPS receiver is via an RS-232 serial port. The data
stream from the GPS receiver is parsed in multiple places in order to receive latitude, longitude and time
data. The following messages may be displayed when the RC4500 is attempting to receive data from the
GPS:
** NO GPS PRESENT **. This message indicates that the gps_present item in the System Definition
(
5.2.1.3.1) configuration item as been set to 0 indicating that no GPS is attached to the RC4500. No
attempt will be made to parse GPS data in this state. If a GPS is truly attached, set the gps_present item
to 1. Note that if the GPS option was not purchased with the controller, the gps_present item will not be
allowed to be set to 1.
**INITIALIZING** or STARTING GPS. This message indicates that the RC4500 has sent a command to
the GPS receiver to start communication. Normally this message should only appear momentarily until
the first response from the GPS has been received.
**GPS OFFLINE**. This message means that no data has received from the GPS. If this message
persists, troubleshooting of GPS communications as described below should be performed.
To check that communication with the GPS is occurring, move to the GPS Serial Port Diagnostics
(
5.2.2.4) screen. The data on the screen should update approximately once a second. If no data is being
displayed or the GPRMC data stream described in 5.2.2.4 is unrecognizable, the integrity of the cabling
between the RC4500 and the GPS receiver should be checked.
**NO GPS NAV**. This message means that correct data streams are being received from the GPS, but
the received data indicates that the GPS has not yet formulated a navigation solution (latitude and
longitude.)
Under normal conditions the GPS should generate a navigation solution within 4 minutes of powering on.
If the GPS has not been powered on for several weeks or if the GPS has been moved a considerable
distance from the last position that it generated a navigation solution, the time it takes to generate a
solution may go beyond 4 minutes. When the GPS is powered up, it assumes it is at the same lat/lon as
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