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Last Modified: February 7, 2020

Indicates that the J1939 session temporarily does not accept long messages.


This property applies to only the CAN J1939 application protocol.

Data type: datatype_icon

Long Name: SAE J1939:ECU Busy

Class: XNET Session

Permissions: Read/Write

Busy is a special ECU state defined in the SAE J1939 standard. A busy ECU receives subsequent RTS messages while handling a previous RTS/CTS communication.

If the ECU cannot respond immediately to an RTS request, the ECU may send CTS Hold messages. In this case, the originator receives information about the busy state and waits until the ECU leaves the busy state. (That is, the ECU no longer sends CTS Hold messages and sends the first CTS message with the requested data.)

Use the ECU Busy property to simulate this ECU behavior. If a busy XNET ECU receives a CTS message, it sends CTS Hold messages instead of CTS data messages immediately. Afterward, if clearing the busy property, the XNET ECU resumes handling the transport protocol starting with CTS data messages, as the originator expects.

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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