Xycom XVME 590 Manual page 64

XVME-500/590 Manual
February, 1988
A software reset (see Section 3.3.1.1) will reset the
flip-flop used to latch the external-trigger pulse, and
abort any conversion in progress.
If an external trigger occurs while the module is in any mode other than the
external-trigger mode, the trigger signal will be latched and a conversion will occur
as soon as the external-trigger mode is entered.
3.4.2 Interrupts
The analog input portion of the module can generate an interrupt to notify the host
that the A/D conversion is complete and the results are available.
vector generated by this interrupt are both user-selectable.
The following three steps must be performed in order to generate an interrupt:
Interrupt level select jumpers must be configured to enable the module
1)
IACK* handling circuitry (see Section 2.5.3).
The Interrupt Vector Register (location base + 83H) must be loaded with
2)
the required vector.
handler when the interrupt is acknowledged.
Interrupts must be enabled via bit D2 in the'status/control register (see
3)
Section 3.3.1.1).
At the completion of a conversion, an interrupt will be generated.
3.4.3 Current Loop Inputs
An A/D input will operate in a 4-20mA or 10-50mA current loop configuration with
the addition of an
should be selected to generate a voltage within the predetermined, jumper-selected
voltage range (0-10V
less than 4mA, and would thus indicate improper operation of the current loop.
Typically, the resistors used would be:
A 500-ohm 1/2W for the 4-20mA configuration,
A 200-ohm 1/2W for the l0-50mA configuration.
This vector register will be read by the interrupt
external current sensing resistor.
max.). A voltage drop of less than IV will provide current of
O R
NOTE
3-20
The level and
The current sensing resistor