FPGA I/O Node

Use an FPGA I/O Node configured for reading with this device.
Note You can synchronize the NI 9237 with other modules that have a selectable timebase source.

Terminals in Software

Use the FPGA I/O Node to access the following terminals for this device.

Table 245. Terminals in Software
Terminal Description
AIx Analog input channel x, where x is the number of the channel. The NI 9237 has AI channels 0 to 3. Do not access AI channels on multiple modules in the same FPGA I/O Node if the modules are not synchronized or do not use the same data rate.
Onboard Clock 12.8 MHz internal clock of the NI 9237.

Use the FPGA I/O Node in a single-cycle Timed Loop to access this channel. Export the Onboard Clock of the NI 9237 to access this channel.

Start Channel that controls when the NI 9237 starts acquiring data.

If TRUE is written to the Start channel, the NI 9237 starts acquiring data. When the NI 9237 is acquiring data, write TRUE to the Stop channel before you can access properties or TEDS information for the module.

If FALSE is written to the Start channel, no operation is performed.
Stop Channel that controls when the NI 9237 stops acquiring data.

If TRUE is written to the Stop channel, the NI 9237 stops acquiring data. When the NI 9237 is acquiring data, write TRUE to the Stop channel before you can access properties or TEDS information for the module.

If FALSE is written to the Stop channel, no operation is performed.

Note For an example of using the Start and Stop channels, refer to the NI 9237 Getting Started VI in the labview\examples\CompactRIO\Module Specific\NI 9237\NI 9237 Getting Started\NI 9234 Getting Started.lvproj.

Arbitration

This device supports only the Arbitrate if Multiple Requestors Only option for arbitration. You cannot configure arbitration settings for this device.

Methods

This device does not support any methods.

I/O Properties

Use the FPGA I/O Property Node to access the following I/O properties for this device.

Table 246. I/O Properties
Property Description
Half-Bridge Enable Controls the half-bridge completion option for each channel.
LSB Weight Returns the LSB weight in units of 100 fV/V per LSB for the channel. 100 fV is equal to 10-13 volts. Use this value to convert and calibrate NI 9237 data if you set the Calibration Mode to Raw in the C Series Module Properties dialog box.
Offset Returns the calibration offset in units of 10 nV/V for the channel. Use this value to convert and calibrate NI 9237 data if you set the Calibration Mode to Raw in the C Series Module Properties dialog box.
Offset Cal Enable Enables offset calibration. This disconnects both signal input pins and forces the channel inputs to zero.
Shunt Cal Enable Controls the shunt calibration switch for each channel.

Module Properties

Use the FPGA I/O Property Node to access the following module properties for this device.

Table 247. Module Properties
Property Description
Data Rate Sets the rate at which the NI 9237 acquires data.
Excitation Voltage Sets the excitation voltage level. All channels share the same excitation voltage.
Module ID Returns the module ID, 0x73A4 (NI 9237 with DSUB) or 0x71C3 (NI 9237 with RJ-50).
Serial Number Returns the unique serial number of the module.
Vendor ID Returns the NI vendor ID, 0x1093.

Single-Cycle Timed Loop

Use the Onboard Clock channel in the single-cycle Timed Loop. You cannot use the other channels on the NI 9237 with the single-cycle Timed Loop. For information about loop timing for this module, refer to Understanding Loop Timing (FPGA Interface).