Module Configuration

CompactRIO Reference and Procedures (FPGA Interface)

Edition Date: June 2010

Part Number: 370984T-01

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Separate configuration properties are provided for each CAN port on the module, labeled as tabs CAN0 and CAN1. The tab labeled Module provides configuration properties that apply to all CAN ports on the module.

The configuration properties are downloaded to the CAN module each time your FPGA VI runs. The configuration properties are saved as part of the LabVIEW project file as well as the FPGA VI image.

This module configuration often makes it possible for you to avoid setting properties in the VI, and focus on CAN Input/Output within the FPGA VI diagram.

CAN Port Properties

The CAN0 and CAN1 tabs provide configuration properties for their respective CAN port.

Baud Rate

This specifies the baud rate (bit rate) to use for CAN communication. Typical CAN baud rates are listed as kilobits per second (kbps).

The default baud rate for the NI 9852 module is 125.0 kbps, which is the typical baud rate used for low-speed transceivers. The default baud rate for the NI 9853 module is 500.0 kbps, which is the typical baud rate used for high-speed transceivers. If you prefer to specify the baud rate as bit timing register values, refer to CAN Advanced Port Configuration.

Auto Start

This Boolean property indicates whether to invoke the Start method automatically when the FPGA VI runs. The default is TRUE (enabled).

When Auto Start is TRUE (enabled), the Start method is invoked automatically when the FPGA VI runs, and the Stop method is invoked automatically when the FPGA VI stops running. This enables your FPGA VI diagram to begin using CAN Input and CAN Output nodes without first using an explicit Start method.

When Auto Start is FALSE (disabled), the Start method is not invoked automatically. You must use the Start method in your FPGA VI diagram in order to start communication. The behavior for Stop is the same as when Auto Start is TRUE, in that the Stop method is invoked automatically when the FPGA VI stops running.

Listen Only

This Boolean control indicates whether to enable the Listen Only feature for passive monitoring of the network. The default is FALSE (disabled).

When Listen Only is FALSE (disabled), you can transmit CAN messages normally using CAN Output. When CAN messages are received, those messages are acknowledged.

When Listen Only is TRUE (enabled), you cannot transmit CAN messages. When CAN messages are received, those messages are not acknowledged. The Philips SJA1000 CAN controller enters error passive state when Listen Only is enabled. Checking Listen Only enables passive monitoring of network traffic, which can be useful for debugging scenarios in which only one device exists on the network.

LS/FT Termination

This control is applicable only for the NI 9852 low-speed/fault-tolerant modules. This control enables the setting of the LS/FT port termination to either 1 kiloohm or 5 kiloohm.

Advanced

This button displays a dialog to configure advanced properties for the CAN port. Refer to CAN Advanced Port Configuration for more information.

Module Properties

The Module tab provides configuration properties that apply to all CAN ports on the module.

Module Clock

Performance of the I/O, methods, and properties is determined by the speed of communication between LabVIEW FPGA and the module. This speed is limited to 20MHz on the CompactRIO Reconfigurable Embedded System, and 10MHz on CompactRIO R Series Expansion system. In order to write CAN applications with consistent performance regardless of LabVIEW FPGA target, the Module Clock property allows you to select 10MHz for the CompactRIO Reconfigurable Embedded System.

For the CompactRIO Reconfigurable Embedded System, the default Module Clock is 20MHz, but you can select 10MHz for compatibility with the CompactRIO R Series Expansion system.

For the CompactRIO R Series Expansion system, the only selection for Module Clock is 10MHz.

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