NI 9237 (FPGA Interface)

CompactRIO 4-Channel, 24-Bit Half/Full-Bridge Analog Input Module

FPGA I/O Node

You can use an FPGA I/O Node, configured for reading, with this device.

Note  You can synchronize an NI 9237 module with other NI 9225/9229/923x modules.

Terminals in Software

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

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. You must 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, you must 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. Refer to the NI 9237 Getting Started VI in the labview\examples\CompactRIO\Module Specific\NI 9237\NI 9237 Getting Started directory for an example of using the Start and Stop channels.  Open example
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, you must 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. Refer to the NI 9237 Getting Started VI in the labview\examples\CompactRIO\Module Specific\NI 9237\NI 9237 Getting Started directory for an example of using the Start and Stop channels.  Open example

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 properties for this device.

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/LSB 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 properties for this device.

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.
Serial Number	Returns the unique serial number of the module.
Vendor ID	Returns the National Instruments vendor ID, 0x1093.

Single-Cycle Timed Loop

You can 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. Refer to the Understanding Loop Timing for the NI 9225/9229/923x topic for information about loop timing for this module.

Hardware Documentation

Refer to the NI 9237 Operating Instructions and Specifications to learn about module specifications and how to use the module. Refer to the CompactRIO Related Documentation for further information about CompactRIO documentation.