2.2 DRIVE SELECT
The Drive Select line enables the controller to select and address the
drive. Control cable interface options may use either a daisy-chain
or
radial configuration.
Pins 15-16 shorted enables Drive
Select 1
Pins 13-14 shorted enables Drive Select 2
Pins
11-12
shorted enables Drive Select 3
Pins
9-10 shorted enables Drive Select 4
2.2,1 DAISY-CHAIN/RADIAL DRIVE CONFIGURATIONS
The ST251/251 R/277R can be configured in either a daisy-chain
or
radial mode. The radial option is enabled by shorting pins 1 and 2 at
J7. The resistor termination pack must remain
installed on any radially
configured drive.
In
a daisy-chain configuration, the last drive in a chain must have the
resistor termination pack
installed.
2,3 WRITE FAULT LATCH OPTIONS:
JP1
AND J7
These options allow the user to configure the Write Fault reset to spe-
cific system requirements.
JP1
has three
jumper
pads, and is located adjacent to the 34-pin
J1
connector. Figure 7 on
page
2-1
illustrates
JP1
and indicates pin-1.
J7
is located midway between the PCB edge-connectors (see
1/2.1
Drive
Configuration
Shunt J7" on
page
2-1).
STANDARD: 1 and 2 jumpered
on
JP1
Write Fault will be cleared when Write Gate is false. A Write Fault
will
only occur when Write Gate is true.
LATCHED: 2 and 3 jumpered on
JP1
This option will maintain Write Fault true after Write Gate goes false
and is recommended for
controllers that
do
not edge-detect Write Fault.
2-2
ST251
1251
RI277R Product Manual, Rev.A
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