Specifications

Doc Number: VIS-ANA-VER-01001-9002
Date: 27 May 2004
Issue: 5.0
Page: 46 of 80
Author: J. Delgadillo
Controls Preliminary Design Report Issue 5.doc
4.2.5.9 CASS LCU Interface
Refer to Figure 4.2.2.1.D, LCU Interface Block Diagram, it shows the handshaking, status,
command and feedback information between the CASS PDU and the CASS LCU. As with
the AZ/ALT PDU, a manual, mechanical switch in the CASS PDU will be provided to ensure
that all LCU Interfaces are identical.
Following are the CASS PDU to Cassegrain LCU interfaces.
TABLE 4.2.2.2.B - CASS PDU to CASS LCU Interfaces
SIGNAL
#
SIGNAL NAME SIGNAL TYPE
CONTROL COMMAND-STATUS
1 CASS Rate Demand +/- 5 Vdc, +VE = +VE rate
2 CASS Rate Scale Factor OCS Low = 3.6 deg/s, High = 0.36 deg/s
3 CASS Enable Command OCS Low = Enable
4 +12V Relay +12V DC Relay power (For items 2,3,35)
5 CASS Actual Rate Scale Factor DCC. Contacts Open = 3.6 deg/s, Closed
= 0.36 deg/s
6 CASS LCU Available DCC. Contacts Closed = CASS LCU
Available
7 CASS LCU Enabled DCC. Contacts Closed = CASS LCU
Enabled
8 CASS LCU Active DCC. Contacts Closed = CASS LCU
Active
9 CASS Axis Enabled DCC. Contacts Closed = CASS Axis
Enabled
10 CASS Summary Fault DCC. Contacts Open = CASS Axis Fault
11 Status Common Isolated Return for above contacts
RELAYS
12 CASS Brakes Released DCC. Contacts Closed = Brakes Released
13 CASS Neg-Pos Interlock Limit DCC. Contacts Open = Limit (I) (SF)
14 CASS CCU Off DCC. Contacts Open = CCU Off
15 CASS Stow Pin Engaged Intlk DCC. Contacts Open = Pin Extended (I)
(SF)