Appendix; Can Bus Basics; Call Station Extension - Dynacord DPC 8000 Manual

34 en | Appendix
11

Appendix

11.1

CAN bus basics

The CAN bus uses a bus or line topology as its network topology. This means that all
participants are connected to a single twisted pair cable (shielded or unshielded), where the
cabling must run from one bus participant to the next. As a result, each device can
communicate with any other device without any limitations. The CAN bus must terminate at
both ends with a 120-ohm load resistor. If the termination is missing or incorrect,
malfunctions can occur as the signal on a bus is reflected at both ends of the bus. This signal
is distorted when the reflections overlap with the original signal, which can lead to data loss.
To prevent or minimize reflections at the bus ends, terminators are used, which "absorb" the
energy of the signal. Since the CAN interface is galvanically isolated from the remaining circuit
parts in many EVI audio devices, a shared earth cable (CAN_GND) is added to the network
cabling (see the following diagram). In this way, it is ensured that all CAN interfaces in the
network have the same potential.
Figure 11.1: CAN bus
11.2

Call station extension

A maximum of five call station extensions (type DPC 8120) can be connected to the DPC 8015
call station. The DPC 8120 call station extension has 20 customizable function and speed dial
buttons. A maximum of five call station extensions can be installed on one call station. Each
button on the call station extensions has a green and a yellow LED, and the buttons are
labeled in the same way as for the call station. In other words, the labels are protected by a
transparent covering, and can be changed at any time. The call station can still be used as a
standing or flush-mounted device even with call station extensions installed. Like the call
station, the call station extension is monitored internally. If an error occurs, this is recorded in
the error log of the PROMATRIX 8000 system.
28-Feb-2013 | |
DPC 8000