User`s manual

Agilent E1330B Digital I/O Module Register Information 111
Appendix B
Register Descriptions
The following pages detail register descriptions of the Digital I/O module.
Manufacturer
Identification
Register
The Manufacturer Identification Register is a read-only register at address
00
16
(Most Significant Byte (MSB)) and 01
16
(Least Significant Byte
(LSB)). Reading this register returns the Agilent Technologies
identification, FFFF
16
.
Device
Identification
Register
The Device Identification Register is a read-only register accessed at address
02
16
. Reading this register returns the Digital I/O module identification of
50
16
for the Agilent E1330A or 51
16
for the Agilent E1330B. Reading
address 03
16
always returns FF
16
.
Card Status/
Control Register
The Card Status/Control Register is a read/write register accessed at address
04
16
and 05
16
. The following table shows the register bit patterns.
SR (soft reset) Writing a "1" and then a "0" to this bit resets all Digital I/O module
components. SR disables all output ports (all ports become input ports) and
sets all other registers to default values. Reads and writes to the other module
registers will not transfer valid data when SR is asserted. This bit is cleared
by a hard reset.
IEN (Main Interrupt Enable) Writing a "1" to this bit allows interrupts from port controller ICs to assert
interrupt on the VXIbus. Writing a "0" masks these interrupts. This bit is
cleared by a hard reset, but not by a soft reset.
Caution A potential race condition exists when clearing this bit or
masking interrupts by means of register 08
16
through 0B
16
.
If an interrupt occurs just before interrupts are masked, it could
be asserted on the VXIbus but not acknowledged by the Digital
I/O module. Use care in disabling interrupts once they have
been enabled.
I(0-3) Interrupt Flags for
ports (0-3) (0 = interrupt).
The MSB of this register is the module's interrupt response vector. It is
asserted on the VXIbus during an interrupt acknowledge cycle.
Address base+04
16
Address base+05
16
1514131211109876543210
1111I2I3I0I11IEN11111SR