User's Manual Part 1

46 OEMV Family Installation and Operation User Manual Rev 5B
Chapter 3 Installation and Set Up
3.3.3 CAN Bus
A Controller Area Network Bus (CAN Bus) is a rugged differential serial bus with a protocol that
provides services for processes, data and network management.
CAN Bus is a generic term, as well as referring to a specific standard for several rugged differential
bus standards that provide services for processes, data, and network management. NovAtel’s
MINOS5 ASIC incorporates a CAN Bus controller and the GPS engine creates and interprets the
physical level signals, and low-level messages, that are compatible with the appropriate sections of the
J1939 and ISO11783 standards. However, the integrator must be aware that there is no single software
standard for such development, and a manufacturer can specify messages that are specific to its
equipment without violating the standards. Accordingly, NovAtel allows integrators to support the
protocol stack they require, to interface to NovAtel’s device drivers, by incorporating this protocol
stack within NovAtel’s Application Program Interface (API). Integrators interested in this option are
advised to contact NovAtel Customer Service for further information.
On the OEMV-1, OEMV-1G and OEMV-2 card, the CAN port is shared with the EVENT2 input on
both cards, the VARF output on the OEMV-1/ OEMV-1G, and the GPIO signal on the OEMV-2. The
OEMV-1, OEMV-1G and OEMV-2 require external CAN transceivers and proper bus terminations.
See Section A.2, OEMV-1 Card on Page 135, or Section A.4, OEMV-2 Card on Page 147, for pin-out
information.
The OEMV-3 has two CAN transceivers, CAN1 and CAN2. See Figure 55, Top-view of 14-Pin CAN
Connector on the OEMV-3 on Page 155. Proper bus termination is required. CAN1 is for slow speed
(up to 125 Kb/s) and CAN2 is for high speed (up to 1 Mb/s). Their CAN interface can be accessed
using NovAtel's API, but requires that shared signals be disabled in order to avoid conflicts. Refer to
the OEMV Firmware Reference Manual and, see also, Table 9 on Page 47.
CAN Bus signals are not available on DL-V3, ProPak-V3 or FlexPak receivers. There is a CAN Bus-
capable model of the SMART-V1 with its own multi-cable.
 CAN Bus functionality is controlled through NovAtel’s optional API software. The API
header file includes documentation on using the CAN bus. For example, oemapi.h.