The CAN Device block allows you to define custom J1939 formatted receive and transmit messages. This tutorial will demonstrate how to use this function block.
CAN Device Function Block
- Signal Input - variables received from the device
- Signal Output - variables that will be transmitted to the device
- Device - any piece of hardware on the CAN bus with a unique source address that can transmit and or receive J1939 formatted data.
- Sequence of variables in the list will be by order variables are created, they can be reordered by selecting and moving them.
- Source Address - This is the source address of the connected device. A message will only be received if it comes from the specified source address.
- Hover over the question mark icon for a description of other parameters.
Transmit Messages Tab
- These are the messages the device will transmit to the uControl Controller.
- Define the PGN and variables for the messages which will be considered signal inputs.
- Expands the list of variables for each PGN.
- The + symbols are used to add new PGN's or new variables.
- The PG Length will display how many bytes have been allocated, this must match the number of bytes the device will be transmitting. A mismatch will result in an error.
- The tool icon next to a PGN or a Variable will display a pop up window with additional parameters to set.
- Multiplexed Messages - The PG tool icon will display the filter settings for this PGN if needed for a Multiplexed message. Discriminator setting allows selecting any variable the user has defined to be used as the message id filter. The Discriminator Value is a numeric value that the message id variable in a incoming message must match.
Receive Messages Tab
- These are messages the uControl Controller will transmit to the device.
- Navigation and building messages is the same as on the Transmit tab.
- Transmit Trigger - Sets the transmit parameters for each PG. Each PG has its own setting. Select Tool Icon to access this setting. There are three trigger options available.
- Cyclic - repeats continually at the rate selected
- Presence Detected - One shot message at power up, wakeup from sleep, or watchdog reset if device is detected on the bus. Used to configure devices at power up.
- User Logic - Triggered when user created logic is true - be careful using this option else the message could be transmitted every logic cycle of 10-20mSec.
- Duplicate Node - If you have sequentially ordered variables with a numeric suffix like Analog 1, Analog 2, Ace will automatically populate the next variable in order when you select the the duplicate button and fill in the Start Byte/Start Bit/Length as appropriate.
- Recalculate Position - If you have a series of variables entered for a PG that are in sequential order but forgot one, you can add it at the end, drag it into the correct position, then select Recalculate, all the Start Byte/Bit information will be automatically recalculated in the new order.