Table Of Contents

Interface:CAN:64bit FD Baud Rate

Last Modified: September 16, 2019

Sets the fast data baud rate for CAN FD+BRS CAN:I/O Mode. The default value for this interface property is the same as the cluster's FD baud rate in the database.

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You can modify this property only when the interface is stopped.

Data type: datatype_icon

Long Name: Interface:CAN:64bit FD Baud Rate

Class: XNET Session

Permissions: Read/Write

Your application can set this property to override the value in the database.

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This property replaces the former 32-bit property. You still can use the baud rate values used with the 32-bit property. The new custom 64-bit baud rate setting requires using values greater than 32 bits.

When the upper nibble (0xF0000000) is clear, this is a numeric baud rate (for example, 500000).

NI-XNET CAN hardware currently accepts the following numeric baud rates: 200000, 250000, 400000, 500000, 800000, 1000000, 1250000, 1600000, 2000000, 2500000, 4000000, 5000000, and 8000000.

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Not all CAN transceivers are rated to transmit at the requested rate. If you attempt to use a rate that exceeds the transceiver's qualified rate, XNET Start returns a warning.

When the upper nibble of the lower 32 bit is set to 0xA (that is, 0xA0000000), the remaining bits provide fields for more custom CAN communication baud rate programming. The fields are shown in the following tables:

63..32 31..28 27..0
Normal Res b0000 Baud Rate (200 k–8 M)
63..56 55 54..47 46..40 39 38..32 31..28 27 26..13 12..8 7..4 3..0
Custom 64-bit Res TDC Res TDCO Res TDCF b1010 Res Tq DTSEG1 DTSEG2 DSJW

Transmitter Delay Compensation (TDC) enables or disables the TDC feature.

  • 0: TDC is disabled.
  • 1: TDC is enabled.

Transmitter Delay Compensation Offset (TDCO) defines the distance between the delay from transmit to receive point and secondary sample point. Valid values are 0–127.

Transmitter Delay Compensation Filter Window Length (TDCF) defines the minimum value for the secondary sample point position. It is enabled when TDCF is greater than TDCO. Valid values are 0–127.

Time quantum (Tq) is used to program the baud rate prescaler. Valid values are 25–800, in increments of 25 ns.

Data Time Segment 1 (DTSEG1) is the data time segment before the sample point. Valid values are 1–31. DTSEG1 is described in the Bosch M_CAN Controller Area Network User’s Manual, Revision 3.2.1. The actual hardware interpretation of this value is one more than the programmed value.

Data Time Segment 2 (DTSEG2) is the data time segment after the sample point. NTSEG2 is described in the Bosch M_CAN Controller Area Network User’s Manual, Revision 3.2.1. The actual hardware interpretation of this value is one more than the programmed value.

Data (Re-)Synchronization Jump Width (DSJW). Valid programmed values are 0–15. The actual hardware interpretation of this value is one more than the programmed value.

32-bit baud rate property

The following information is valid for the former 32-bit Baud Rate property that was replaced by the 64bit property. You still can use the baud rate values used with the 32-bit property.

When the upper nibble is set to 0x8 (that is, 0x80000000), the remaining bits provide fields for more custom CAN communication baud rate programming.

  31..28 27..26 25..24 23..20 19..16 15..10 9..8 7..0
Custom b1000 Res SJW (0–3) TSEG2 (0–7) TSEG1 (1–15) Res Tq (25–800)

(Re-)Synchronization Jump Width (SJW). Valid programmed values are 0–3. The actual hardware interpretation of this value is one more than the programmed value.

Time Segment 2 (TSEG2) is the time segment after the sample point. Valid programmed values are 0–7. TSEG2 is the Phase_Seg2(D) described in Bosch's CAN with Flexible Data-Rate Specification, Version 1.0. The actual hardware interpretation of this value is one more than the programmed value.

Time Segment 1 (TSEG1) is the time segment before the sample point. Valid programmed values are 1–0xF (1–15 decimal). TSEG1 is the combination of the Prop_Seg(D) and Phase_Seg1(D) described in the Bosch CAN with Flexible Data-Rate Specification, Version 1.0. The actual hardware interpretation of this value is one more than the programmed value.

Time quantum (Tq) is used to program the baud rate prescaler. Valid programmed values are 25–800, in increments of 25 ns.

Formulas

Baud rate = (Total Ticks per Sec / Ticks for 1 bit ) = (Oscillator Frequency[Hz] * Tq[Ticks]) / 25) / (Sync_Seg[Ticks] + TSEG1[Ticks] + TSEG2[Ticks])

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NI XNET devices use 40 MHz oscillators.

Sample Point = (TSEG1 + Sync_Seg) / (TSEG1 + Sync_Seg + TSEG2)

Where This Property Is Available:

Desktop OS: Windows

FPGA: Not supported

Web Server: Not supported in VIs that run in a web application


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