The CANobserver® from GEMAC is a diagnostic device which is used for physical and logical long-term monitoring of CAN bus systems and has been designed as a stationary supplement to the CAN-Bus Tester 2. The CANobserver® is permanently implemented into the network, continuously monitors the data transfer and records it automatically for a period of up to ten years. On the basis of the physical properties of the CAN-Bus it recognizes system errors right in time and reports them immediately to the plant operator.

A slowly deteriorating signal quality can be detected in good time to avoid expensive system standstills. The CANobserver® is a unique device which ensures status-oriented maintenance. VDI/VDE has recognized this necessity as well. The new guideline 2184, published in 2007, explains how plant operators can guarantee reliable functioning and maintenance of their field bus systems.

New: CANobserver remote diagnostic system now also adapted for use with mobile devices
  • Bus systems:
    • CAN, CANopen, DeviceNet, SAE J1939
  • Baud rates (5 kbit/s ... 1 Mbit/s)
  • Monitoring, physical:
    • General quality level (0 ... 100 %)
    • Disturbance-free voltage range
    • Rising and falling edges
  • Monitoring, logical:
    • Active/passive errors, overload frames, ack. errors
  • Continuous monitoring
    • Bus status, bus traffic load, CAN supply voltage
  • User-friendly browser-based configuration and analysis, control point connection via SNMP
  • Email notification (device, status and error notification)
  • Maintenance without the need for a host-PC, continuous recording of data up to 10 years
Fields of Application:

  • Real-time monitoring of CAN bus plants
  • Plant monitoring according to VDI/VDE2184

General parameters and overview of functions

Use (CAN type)

CAN (ISO11898-2), CANopen, DeviceNet (EN 50325-2), SAE J1939

Baud rates

All baud rates according to the particular CAN type

Station overview

Automatically according to the particular CAN type

Bit sampling


Quality level

Signal quality level (0 ... 100 %)

Disturbance-free voltage range

0 ... 4 V, resolution 50 mV


Edge steepness (in 1/64th of the bit width)

Bus status

Bus traffic detection (display: dominant, recessive, not defined, bus traffic)

Bus traffic load

Permanent display of the bus traffic load (0 ... 100 %)

Error logging

Active error frames

Passive error frames

Overload frames

Acknowledge errors

Failure to reach a critical quality level (adjustable)

Failure to reach a critical disturbance-free voltage range (adjustable)

Exceeding of a critical rising edge (adjustable)

Exceeding of a critical falling edge (adjustable)

Error indicator

All logged errors (permanent/current) displayed via LEDs

Error output

Freely programmable


Recorded measurements exportable in XML format for processing with CAN-Bus Tester 2 - Application software

Electrical parameters

Power supply

Via the supplied wide-range power supply pack (9 ... 36 V DC)

Measuring of the differential voltage

typ. - 0.75 V ... 3.00 V

Measuring of the CAN supply voltage

0 ... 36 V

Error output

Potential-free, max. 30 V DC

Mechanical parameters

CAN connection

9-pin SUB-D connector

Network connection

10/100 MBit Ethernet IEE 802.3u, RJ-45 (8P8C) LAN connector


Aluminum plate housing for top hat rail mounting, degree of protection: IP20

Temperature range

Operation: 5 ... 40 °C, storage: - 20 ... 60 °C


50 mm x 125 mm x 124 mm


approx. 550 g