Automatic Message Transmission

In the MxSuite test environment, transitions are delivered to and from the SUTs.  A typical way to cause a stream of transitions to be delivered to the SUT is to define a transition pattern for a Signal in a TestCase. With message Signals (and especially with bus traffic), there are often a set of rules that define the automatic transmission of transition data.  The automated creation and transmission of message transitions can be based either on the change in a Signal value or the passage of time. MxTransIt provides a feature for users to configure automatic transmission of any messages.  This feature allows you to automate the transmission of 'heartbeat messages' required for some applications,  so that you can focus on the Signal's values in the TestCases.  Moreover, this feature allows you to edit message-based Signals (fields of the message) as normal numeric, Boolean, and message Signals.

The Automatic Message Transmission strategy is defined in the CAN Database (DBC file) associated with a CAN bus. This file is typically provided by the automobile manufacturer. The file must include the GenMsgSendType and GenMsgCycleTime attributes. To modify the transmission strategy permanently, edit the DBC file using the Vector CANdb++ Editor. The automatic transmission strategy can be modified during execution of a test by using the System Signal called MxV Auto Msg Cfg.

Note that automatic transmission of messages is enabled or disabled by the MxV Auto Msg Tx System Signal. It is enabled by default. To change it, add the Signal to a TestCase.

Changing Values

By default, MxVDev sends out all periodic messages described in the CAN database with default values defined in the DBC file. To change the value of a Signal contained in a periodic message, you need to explicitly set the Signal value. Add the Signal to a TestCase and use the graphic Signal editor to set the new value. That value is transmitted in the field of the periodic message until you change it again. All non-explicitly defined fields remain at the DBC default.

Note that if you add a periodically transmitted message to a TestCase and set it to a particular data value, that message with that value will be sent just once. Subsequently the message value reverts to that defined by the DBC defaults, modified by any explicitly defined Signal values.

Auto Message Transmission System Signals

MxVDev provides System Signals for users to control the auto message transmission:

MxV Auto Msg Tx: This system Signal is to enable/disable the auto transmission of all messages. It is a binary Signal with only two possible values: 0 and 1. When the value is 0, the auto transmission of all messages is disabled; when 1, transmission is enabled.

MxV Auto Msg Cfg: To change message settings, right-click on a transition in this Signal in the Job window to display the following:


This System Signal enables you to:

oReinitialize all messages' settings. When this option is selected the automatic transmission cycle is restarted from the beginning.  Transmission of every message is enabled, and the cycle time is reset back to its normal value.

oChange message settings. This option allows you to change some of the auto-transmission settings on the fly.  Specifically, you can:

Modify Auto-Transmission state.  If you want to change whether auto-transmission is on or off, first check the box labeled Modify Auto-Transmission state.  Then select Enable or Disable to change the state.

Modify cycle time.  If you want to change the Cycle Time (periodic transmission rate) of the message, first check the box labeled Modify Cycle Time.  Enter the desired Cycle Time in the Cycle Time field. You can change the cycle time for both cyclic and spontaneous messages. See Changing the Cycle Time with MxV Auto Msg Cfg.

There are other System Signals that control automatic message transmission:

The MxV Module Reset System Signal clears any modifications made by MxV Auto Msg Tx or MxV Auto Msg Cfg.

The MxV Auto Node Tx System Signal controls the auto transmission of periodic messages from a particular node on a Bus.

See Bus Control System Signals for all bus control Signals.

hmtoggle_plus1Changing the Cycle Time with MxV Auto Msg Cfg


Related Topics:

Bus Overview

System Signals

Using the Signal Dictionary

CAN Transmit Driver–Bus Control Signals