and applied to the Q inputs of U7 are equal, the P=Q output pin
of U7 will assert lowlighting the slaveSelect LED and indicating
the monitor is accessing the cabinet data. The monitor can than
read or write to the slave to access status and analog channels.
CABINET ADRRD* FUNCTION
0 Status modules 1-8
01 Status modules 9-16
02 Status module 17
Spare 1-3
PS1&2faults
Door & Air
03 Options to be determined
04 Options to be determined
05 Options to be determined
06 Options to be determined
07 Options to be determined
The various status points can be read by the monitor by first
issuing an address, then reading the data from the cabinet con-
troller.
4.2.8.6 Cabinet ON/OFF Control (sheet 2)
Cabinet ON/OFF control is connected to the slave controller at
J-2 by a three conductor cable to optocoupler U23 and passed on
to U2, the TX ON/OFF latch. The TX ON/OFF latch controls the
state of the AC contactor and 50 volt power supplies in the
cabinet. The TX latch cannot beset to the ON state if is a RESET,
DOOR, or CAB OFF command is present at the reset input of
U2. However, pressing the slave CAB OFF button will override
the main controller CAB ON command as long as the button is
held in. When the button is released, the main controller CAB
ON command will turn the cabinet back on.
The STSET one shot U22 is used to re-enable modules that have
faulted without turning off the other on-air modules. A module
is re-enabled by asserting its enable line low; however, momen-
tarily asserting the enable lines low for all modules in the cabinet
would disable them for the length of the pulse. Pressing the
transmitter ON button will cause a short pulse on the CAB ON
line, causing U22 to fire and thus pulsing only the enable lines
of faulted modules.
4.2.8.7 Power Supply Control (sheet 2)
The two 50 volt power supplies are enabled by U58, closing the
current loop to the optocouplers on the 50 volt supply control
board which starts a controlled ramp up to 50 volts DC. In order
for U58 to enable the supplies, the following conditions must be
met:
a. The TX ON/OFF latch must be set to ON.
b. The blower must be running and the AIR switch closed.
c. The door must be closed.
TheaboveconditionswillenableU58,closingthepoweron loop.
If a power supply faults off, it can be re-enabled by pressing the
transmitter ON button. This will cause the CAB ON lines to
pulse, which in turn will fire the STSET one-shot gated to U15.
Thiswillcausethefailedpowersupply PS1 CTRL signalto pulse
high for about 500 mS to reset the fault logic and enable the
supply again.
4.2.8.8 Fault Detection Logic (sheet 2)
The fault detection circuitry detects status from AIR SWITCH,
DOOR OPEN, POWER SUPPLY 1, and POWER SUPPLY 2 in
order to interlock the cabinet AC or DC control signals. All these
faults are summed together through U17, U18, and U25 to the
red LED on the front panel of the slave controller. When the
transmitter is in the OFF state, only the door interlock is reported
by the monitoring system.
When the transmitter ON button is pressed, the TXD line is set
to a logic 1, allowing the air fault to light the air loss and power
supply fault indicators. When the blowers have established cabi-
net pressure, the air switch will close, cancelling the airloss fault.
After about 0.8 seconds, the 50 volt powersupplies should return
STATE TXD MODF STSET PS1SET PS2SET OUT
1 1 X X X X X FORCE ALL ENABLES TO OFF
(1)
2 0 1 X X X 0 MODULE NOT SELECTED
(EN=1)
3 0 0 X X X 1 MODULE IS ENABLED (EN=0)
4 0 1 0 X X 0 FORCE MODULE RESET (EN=1)
501X 0 X 0
601X X 0 0
Asserting STSET will enable any module with MODF=1
Asserting PS1SET will enable any odd numbered module that has a MODF=1
Asserting PS2SET will enable any even numbered module that has a MODF=1
If MODF=0 STSET, PS1SET, PS2SET will not affect module operation and the module will stay on the air
If MODF=1 the module is not enabled or a module fault has disabled the module
IfMODF=0themoduleENABLE/RESETlineisalso=0
Table 4-1. PAL Logic
Slave Controller Module ENABLE
Section IV - Theory of Operation
888-2365-001 4-7
WARNING: Disconnect primary power prior to servicing.
To Next Page
Loading...
