Selecting a base address 3, Fault indicator 3, Status register 3 – Sensoray 421 User Manual
Page 5: Selecting a base address, Fault indicator status register, Sensoray model 421 instruction manual page 3, First address nibble (msb), Third address nibble
Sensoray Model 421 Instruction Manual
Page 3
Selecting a Base Address
First Address Nibble (MSB)
Adrs
S1-15
S1-14
S1-13
S1-12
0
On
On
On
On
1
On
On
On
Off
2
On
On
Off
On
3
On
On
Off
Off
4
On
Off
On
On
5
On
Off
On
Off
6
On
Off
Off
On
7
On
Off
Off
Off
8
Off
On
On
On
9
Off
On
On
Off
A
Off
On
Off
On
B
Off
On
Off
Off
C
Off
Off
On
On
D
Off
Off
On
Off
E
Off
Off
Off
On
F
Off
Off
Off
Off
Fault Indicator
Status Register
A status register, located at the board base address
+ 11, makes available four status bits for access by
the ISAbus host processor. The status register is
organized as follows:
STATUS (11):
Status bits are all active high and have the
following definitions:
UN — indicates A/D converter is programmed for
unipolar operation.
BZ — indicates that the A/D converter is busy
digitizing an analog input.
DE — indicates that all four DAC output channels
have been enabled via the CHCTRL port.
PD — indicates 421 is in the low-power standby
mode, controlled by the RELAY2 port.
x
x
x
x
UN DE BZ FT
A red light-emitting diode located near the upper-
left corner of the circuit board indicates reset and
fault conditions.
In normal operation, the indicator is turned on only
during system or 421 local reset. The indicator
should be off at all other times.
If the fault indicator remains on for more than one
second following a reset, a fault condition may
exist on the board that requires servicing.
Before servicing the unit, make sure that your
ISAbus host CPU is not invoking repeated soft
resets of the 421 (which will also keep the indicator
turned on).
The 421 board occupies a block of 32 consecutive
addresses in the ISAbus 16-bit I/O space. The address
range occupied by the board must begin on a 32-byte
address boundary. The first address in the block — the
“base address” — is assigned by DIP switches S1 and S2.
Care must be exercised to ensure that no other
devices use addresses in the address range
assigned to the 421. Use the tables shown below
to determine the proper address switch settings
for your application.
For example, to program the board
base address to 03A0 hex, set the
address switches as follows: Turn
on S1 switches10-15 and S2
switch 6. Turn off S1 switches 8
and 9. S2 switches 2 and 4.
Note: default switch settings are shown in bold
Second Address Nibble
Adrs
S1-11
S1-10
S1-9
S1-8
0
On
On
On
On
1
On
On
On
Off
2
On
On
Off
On
3
On
On
Off
Off
4
On
Off
On
On
5
On
Off
On
Off
6
On
Off
Off
On
7
On
Off
Off
Off
8
Off
On
On
On
9
Off
On
On
Off
A
Off
On
Off
On
B
Off
On
Off
Off
C
Off
Off
On
On
D
Off
Off
On
Off
E
Off
Off
Off
On
F
Off
Off
Off
Off
Third Address Nibble
Adrs
S2-7
S2-6
S2-5
0
On
On
On
2
On
On
Off
4
On
Off
On
6
On
Off
Off
8
Off
On
On
A
Off
On
Off
C
Off
Off
On
E
Off
Off
Off