Diamond Systems JANUS-MM-LP PC/104 and PC/104-Plus Dual and Quad Isolated CAN Bus Modules with Digital I/O

Vehicles and rugged machines tend to put their sensors, controllers and actuators on a CAN network, and the embedded computer has to join that network without importing its electrical faults. The Diamond Systems JANUS-MM-LP series adds isolated CAN to PC/104 stacks: CAN bus modules with two or four CAN 2.0B ports plus 16 digital I/O lines, in PC/104-Plus and PC/104 versions.

Inside every JANUS-MM-LP module an FPGA core holds the CAN controller and digital I/O logic, with data rates up to 1 Mbps. Each port supports standard 11-bit and extended 29-bit identifiers, with expanded message queues of 16 eight-byte transmit and 31 eight-byte receive entries and 16 receive filters, which helps the host keep up with busy buses. Each port has its own ADM3053 combined isolator and transceiver, giving 500 V isolation port to port and port to host, and jumper-selectable biased split termination for better noise reduction. The 16 digital I/O lines sit in two 8-bit ports with software direction control and jumper-selectable 3.3 V or 5 V logic and pull-up or pull-down resistors.

The series comes in four models. The JNMM-4LP-XT has four CAN ports on PC/104-Plus, and the JNMM-2LP-XT has two. The JNMM-4L-XT and JNMM-2L-XT carry the same four or two ports on the PC/104 form factor for ISA-bus stacks. The host interface selects PCI or ISA automatically, so the choice comes down to which bus the host provides and how many CAN networks the system joins. Diamond offers a digital I/O cable per board and a CAN cable for each port.

All JANUS-MM-LP modules run from 5 V DC and are tested for -40 to 85 °C operation at 5 to 95% humidity, non-condensing, and Diamond Systems specifies them as MIL-STD-202G compatible for shock and vibration. Latching connectors improve retention under vibration, and a basic CAN driver with APIs and a monitor program supports Windows Embedded Standard 7 and Ubuntu Linux 12.04 LTS. On a PC/104 host such as an ATHENA IV SBC, or a PC/104-Plus host such as an ARIES SBC, the series lets one stack act as an isolated CAN node with spare digital control lines.