Network Principles; Bus Line Length; Bus Error / Safety Position Of The Solenoid Valves - Burkert 8681 Guide Rapide

büS / CANopen design
12.6

Network principles

Several aspects must be considered when installing a büS/
CANopen fieldbus system.
• Each "node" requires its own "node ID", each gateway can
control up to 63 "nodes" (max. number applies to control heads
Type 8681 büS).
• The CAN cable must be "terminated" at both ends: Terminate
the end of the CAN cable with a terminating resistor (120 Ω) or,
if the cable ends at a distribution box, connect the terminating
resistor to the CAN OUT connection.
• If the voltage loss is too high, an additional power supply must
be fed into a distribution box (PWR IN connection).
• Observe baud rates and maximum cable lengths (see "12.7")
• A PC with Bürkert Communicator Type 8920 can be connected
for service work and also for reading CAN data.
• Required tightening torque for all M12 plug-in connections
(cables, T-pieces, ...) to ensure the necessary seal tightness
against moisture: 0.6 Nm + 0.1 Nm.
• Seal all open connections tightly with protective caps!
Further details - see Operating Instructions Type 8681.
12.7

Bus line length

The maximum total line length (sum of trunk lines and drop lines)
of a network depends on the baud rate.
The maximum length of a single drop line is 6 m. The maximum
total line length and the maximum total length of all drop lines in
Type 8681
total (according to büS/CANopen specification) depending on the
baud rate (in kbit/s) is as follows for:
Baud rate Max. total length
125 kbit/s 200 m
250 kbit/s 100 m
500 kbit/s 40 m
12.8 Bus error / Safety position of the
solenoid valves
Bus failure is indicated via the central multi-colour device status
display (Top LED). The bus status LED "Network" on the electronic
module ("Fig. 9") also indicates whether a bus error has occurred
without differentiating between special blinking patterns.
Bus errors can be caused, for example, by communication problems
with the gateway or PLC, incorrect addressing of node IDs, incorrect
baud rate.
Safety position of the solenoid valves in the event of a bus
error
If the bus fails, the solenoid valves are switched to a programmable
safety position (default: The solenoid valves are in the power-off
state). For details on the configuration - see Operating Instructions
Type 8681 (chapter "Safety position in case of bus failure").
english
Max. total drop line length
100 m
55 m
30 m
29