© National Instruments
|
2-23
Scaling constants for the TB-4300B are stored in the EEPROM and are used by software to
automatically apply scaling to the signal for the selected range. When using the TB-4300C,
software automatically applies scaling to convert the measurement to current using the nominal
scaling factor of 50. The TB-4300C does not include scaling constants in the EEPROM.
Accessory Auto-Detection
NI SC Express modules automatically detect compatible accessories or terminal blocks.
The RSVD pins on the I/O connector provide power to the accessories as well as digital
communication lines. This allows software to detect when accessories are inserted or removed.
In addition, software can automatically identify the specific terminal block as well as access any
scaling information associated with the terminal block.
MAX allows you to see what accessories are currently connected to your module. In MAX,
expand
Devices and Interfaces
and locate your module. If a terminal block is connected to your
module, it will be displayed beneath the module. Unsupported terminal blocks appear in MAX
with an X next to them.
NI-DAQmx property nodes can be used to programmatically access information about
connected accessories in your application. Refer to the
NI-DAQmx Help
for documentation
about programmatically accessing accessory status. Select
Start»All Programs»National
Instruments»NI-DAQmx»NI-DAQmx Help
.
Accessory Power
The NI PXIe-4300 provides auxiliary power for accessories connected to the module and has
protection in the event of a fault condition. If a fault occurs in the form of an over-power
condition, the power supply latches off until it is reset. To reset after a fault condition perform a
Device Reset in MAX or programmatically in your ADE.
Isolation
Caution
Refer to the
Read Me First: Safety and Electromagnetic Compatibility
,
included with your module, for more safety information.
The NI PXIe-4300 provides 300 V channel-to-channel basic isolation as well as 300 V
channel-to-earth reinforced isolation. This rating is intended for measurements within
Measurement Category II. These isolation levels are verified with a 5second dielectric withstand
test. Refer to the
NI PXIe-4300 Device Specifications
for details.
Measurement Category II is for measurements performed on circuits directly connected to the
electrical distribution system. This category refers to local-level electrical distribution, such as
that provided by a standard wall outlet, for example, 115 V for U.S. or 230 V for Europe.
Do not connect the NI PXIe-4300 module to signals or use for measurements within
Measurement Categories III or IV.
