Specifications

ManualsBrandsVXI ManualsAmplifierVT1508A

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2) When a channel’s SCP filtering is enabled, allow fifteen seconds after turning on

OTD for the filters capacitors to charge before checking for open transducers.

To enable or disable Open Transducer Detection, use the DIAGnostic:OTDetect

<enable>, (@<ch_list>) command.

The <enable> parameter can specify ON or OFF

An SCP is addressed when the <ch_list> parameter specifies a channel

number contained on the SCP. The first channel on each SCP is:

0, 8, 16, 24, 32, 40, 48, and 56

To enable Open Transducer Detection on all channels on SCPs 1 and 3:

DIAG:OTD ON, (@100,116) 0 is on SCP 1 and 16 is on SCP3

To disable Open Transducer Detection on all channels on SCPs 1 and 3:

DIAG:OTD OFF, (@100,116)

More On Auto Ranging

There are rare circumstances where an input signal can be difficult for the

VT1419A to auto range correctly. The module completes the range selection based

on the input signal about 6 µs before the actual measurement is made on that

channel. If during that period the signal becomes greater than the selected range can

handle, the module will return an overflow reading (±INFinity).

The only solution to this problem is to use manual range on channels that display

this behavior.

Settling Characteristics

Some sequences of input signals as determined by their order of appearance in a

scan list can be a challenge to measure accurately. This section is intended to help

determine if a system presents any of these problems and how best to eliminate

them or reduce their affect.

Background While the VT1419A can auto-range, measure and convert a reading to engineering

units as fast as once every 10 µs, measuring a high level signal followed by a very

low level signal may require some extra settling time. As seen from the point of

view of the VT1419A’s Analog-to-Digital converter and its Range Amplifier, this

situation is the most difficult to measure. For example, look at two consecutive

channels; the first measures a power supply at 15.5 volts, the next measures a

thermocouple temperature. First the input to the Range Amplifier is at 15.5 volts

(near its maximum) with any stray capacitances charged accordingly, then it

immediately is switched to a thermocouple channel and down-ranged to its

0.0625 volt range. On this range, the resolution is now 1.91 µV per Least

Significant Bit (LSB). Because of this sensitivity, the time to discharge these stray

capacitances may have to be considered.

Programming the VT1419A Multifunction

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