Research Concepts RC2500 - Manual (Page 148)

RC2500 Antenna Controller Appendix O Replacing the Andrew APC100/ APC 300 141
Research Concepts, Inc. • 5420 Martindale Road • Shawnee, Kansas 66218-9680 • USA www.researchconcepts.com
Setting Soft Limits for RC2500 Controllers which Replace Andrew Products
Introduction
RC2500 software version 1.14 added support for user specified azimuth, elevation, and polarization
limits. The Andrew LMKDS and NPL 9000 antenna interface units (AIU’s) do not provide limit status
information to the RC2500. These AIU’s do process limit information to keep the antenna from moving
past a physical limit but do not provide limit information to the RC2500. The software modification
described here allows a user to input limit information to the RC2500. If the limit information is valid the
RC2500 will not allow movements of the antenna outside of the region defined by the user-specified
limits. When the antenna reaches a limit a limit indication will be displayed in the appropriate position
display field when the controller is operating in a mode where antenna position information is displayed.
Setting the Soft Limits
The user specifies the position of the soft limits via the RC2500’s CONFIG mode. Six additional CONFIG
mode items have been added. These are Azim CCW Limit, Azim CW Limit, Elev Down Limit, Elev Up
Limit, Pol CCW Limit, and Pol CW Limit.
Here is the procedure for setting the soft limits (this assumes that the antenna’s mechanical limit switches
are installed and properly adjusted)…
1. Verify that the Reverse Az Sensor Direction, Reverse El Sensor Direction, and Reverse Pol Sensor
Direction CONFIG mode items have been properly initialized as described in section 3.xx.
2. Verify that the Azim Display Offset, Elev Display Offset, and Pol Display Offset CONFIG mode items
have been initialized as described in section 3.xx.
3. To determine the location of the antenna’s azimuth CCW limit, from the RC2500’s MANUAL mode jog
the antenna in the azimuth CCW direction until the antenna quits moving due to activation of the
azimuth CCW limit switch. Jog the antenna in the azimuth CW direction approximately 3 degrees.
Record the displayed azimuth position. The range of displayed azimuth position values is 0.0 to
359.99 degrees.
4. To determine the location of the antenna’s azimuth CW limit, from the RC2500’s MANUAL mode jog
the antenna in the azimuth CW direction until the antenna quits moving due to activation of the
azimuth CW limit switch. Jog the antenna in the azimuth CCW direction approximately 3 degrees.
Record the displayed azimuth position.
5. From CONFIG mode, initialize the Azim CCW Limit and Azim CW Limit items to the azimuth positions
recorded in steps 3 and 4 above. Be sure to terminate each entry by hitting the ENTER key.
6. The elevation down/up and polarization ccw/cw limits are determined in a similar manner. Note that
the range of displayed elevation positions is –99.99 to 260.00 degrees and the range of displayed
polarization positions is –99.9 to 260.0 degrees.
Corrupted Limits Alarm Messages
The soft limit data is stored in the controller’s non-volatile memory. The controller constantly checks the
validity of non-volatile memory. If the controller detects that any of the limits are corrupt the ‘LIMITS
ALARM’ error message will flash on the bottom row of the display.
Soft Limits Theory of Operation
The RC2500 is designed to interface with antenna’s that employ resolver type position sensors. The
controller employs a resolver to digital converter (RDC) to convert the electrical outputs of the resolver to
a 16 bit digital word. (0 to 65535 – referred to as the resolver position count) This digital word represents
the angular deflection of the resolver input shaft relative to a reference position, 0.00 to 359.99 degrees.
When the resolver output reaches 359.99 (65535) it rolls over to 0.00 (0), this is termed the resolver
rollover point.
The controller displays azimuth positions as an angular value between 0.00 and 359.99 degrees. For the
elevation axis the range of displayed values is –99.99 to 260.00. For the polarization axis, the range of
displayed values is –99.9 to 260.0. The key to understanding the mapping of resolver position to display
angle is to recognize that an indicated position of –99.99 degrees is equivalent to 260.01 degrees.