CAN Communications

The latest firmware and interface definitions files are always available via the web.
Your EPC representative can provide access.

Basic Requirements

CAN communication is accomplished in accordance with SAE J1939 specifications, and uses the proprietary address space defined therein.  Communication requires:

  1. 250 or 500kbps 2-wire bus
  2. CAN 2.0b compatible hardware
  3. 120 Ohm termination at the ends of the bus per CAN 2.0b specification.
  4. 29 bit extended identifiers

 

NOTE: Commands must be sent to the module at a 1Hz rate or faster, or the power module will assume that the controller has gone offline and will shut down in order to protect the system and personnel.

 

PROTOCOL

The provided CAN interface is fully compliant with CAN protocol, version 2.0b (29 bit IDs) and is compatible with SAE J1939 standard networks.  The default data rate is 500Kbps, and data rates up to 1Mbps are supported.

 

CAN TERMINATION

In the standard configuration, the converter’s CAN interface is unterminated, and a 120 Ohm CAN termination must be installed as appropriate by the user.

 

CAN GROUNDING & ISOLATION

The converter’s CAN interface provides galvanic isolation from chassis and control power grounds.  ‘CAN High’ and ‘CAN Low’ should be connected to the host data lines and ‘CAN Ground’ should be connected to the host controller’s CAN ground.


Electrical interface

 

Requirements for establishing communication with the power module:

·             24V control power must be applied to J1

o   18V min to 28V max, 2A nominal, 4.5A max inrush

·             CAN must be connected to J8

 

Hardware Enable Signal

The Hardware Enable signal is designated as Digital Input 0 (DI0).  The input is monitored to allow an external shutdown of the converter independent of the serial CAN interface. 

The default logic of the input is active high, thus the input must be driven (3V to 25V) in order to enter the ENABLED state.

If the input is removed while the inverter is in the ENABLED state, an ESTOP Shutdown fault will be generated.

The logic of the Enable signal may be inverted via a control bit in the CAN interface.  This should be done if the input is driven with active low logic, or if the signal is unused or disconnected.