Research Concepts RC2500 - Manual (Page 139)

132 RC2500 Antenna Controller Appendix N Replacing the NPL 9000
Research Concepts, Inc. • 5420 Martindale Road • Shawnee, Kansas • 66218-9680 • USA www.researchconcepts.com
Appendix N – Replacing the NPL 9000
It is possible to use the RC2500 Antenna Control Unit (ACU) to replace the Northern Precision Labs, NPL
9000 series Antenna Controller and enjoy the industry-standard RCI operator interface and added
capabilities of inclined-orbit tracking, multiple stored locations, and PC remote control. In order to be
compatible with the Antenna and the Antenna Drive Unit (ADU), resolvers are placed on the azimuth,
elevation and polarization pivot points. Information on the connection and use of resolvers is found in
section 3.3.1. The firmware version for this unit is: version 1.14wna--, the date: 4.3.00, and the
checksum: 'XX'. The RC2500 uses a modified 2_5KI_O1 as the interface PCB.
ADU Status Input
The NPL 9000 ADU has a single, 12VDC non-isolated output that is directly compatible with the limit
inputs of the RC2500. This “Local Jog Control Active” signals to the ACU with 12VDC when the ADU is
being driven from the Antenna-Pad-mounted jog controls. In response to this stimulous, the RC2500 will
remove its Drive Supply from the “+” drives lines of the ADU and flash “ALARM – MAINTENANCE” on the
LCD. In this state the RC2500 may not move the antenna. When the 12V signal is removed, the flashing
alarm message disappears, the 12V supply is restored and control is resumed from the RC2500.
The “Local Jog Control Active” terminals of the ADU are connected to a limit input and limit return
terminals of the RC2500. The former ESTOP input (PB7) is used for this input.
The antenna has limit switches to guard against over-travel on all three axes. These limit switches
interface with the ADU. The RC2500 ACU operates with “soft” limits. That is, a given resolver position
entered from the front panel, serves as a limit. The soft limits of course should be “inside” the antenna
limit switches.
The Output of the RC2500 with its 10, 24V x 700mA open-collector drivers is directly compatible with the
drive inputs to the NPL 9000 ADU. There are 6 drive inputs for the ADU. These are: AZ WEST, AZ
EAST, EL UP, EL DOWN, POL CW, and POL CCW. When the NPL 9000 ADU is NOT in “Local Jog
Mode” the entire interface is powered from the RC2500. ADU relays provide isolation between the
grounding system of the RC2500 and the grounding system of the ADU. When “Local Jog Mode” is
asserted at the ADU, the interface is powered by the ADU 12V source.
The standard I/O drive board of the RC2500 is modified to adapt to the NPL 9000 interface. A secondary
regulator, reverse- and over-current protection stage is added to supply the required 12VDC when the
RC2500 is powering the interface. The PC0 relay is used to apply this voltage to the drive interface and
remove it in the case of errors or when the Local jog Mode is active. The six “+” lines of the drive
interface running from the LMKDS are terminated at 3 previously unused pins of J7 supplying the +12V .
The drive side of the RC2500 is also powered
The hardware interface between the RC2500 ACU and NPL 9000 ADU is summarized in the following
tables showing all connections at J6 and J7. Following the interconnection tables, a description of the
unique operating firmware for this version is given.