Redundant Cabling For Dcnm-Aps2/Dcnm-Ps2 Units - Bosch DICENTIS Installation Manual

28 en | System installation design and planning
4.4.1

Redundant cabling for DCNM-APS2/DCNM-PS2 units

This section describes how to create redundant cabling for DCNM-APS2 / DCNM-PS2 type
units. The maximum number of Ethernet devices in the largest possible loop (including the
root switch) is 22. In a system with no Ethernet switch(es), the APS is the root switch.
The total number of devices allowed in a loop depends on:
– The type of device connected in the loop (for example, DCNM-MMD2 devices consume
more power than DCNM-DE devices).
– The length of the loop (cable also consumes power).
The figure shows how to calculate the number of devices in the loop. The grey line shows the
largest loop. The # sign shows the way the devices are counted.
In the example below up to 19 (22 - 3 = 19) discussion devices can be connected.
Figure 4.8: DICENTIS discussion devices connected with redundant cabling between DCNM-PS2 / DCNM-
APS2 type units
1 DICENTIS system
3 DCNM-APS2
5 DICENTIS cabling (redundant loop)
Maximum number of DICENTIS devices in a string:
– The max age timer should be set to 22 when RSTP is used for cable redundancy to
prevent a defective cable or powering switch from influencing the system.
– Each time data hops from one switch to another, the age is increased by one. This timer
can be reached or exceeded, because a daisy chain can be used to loop through the
DICENTIS devices.
– This timer (or restriction) cannot be reached when there is no cable redundancy. This is
because the power limitation will be reached before the max age restriction is reached.
– The timer can be reached when:
–
–
2023-02 (draft) | 4.3-draft |
1
you use cable redundancy,
the system is incorrectly wired.
Installation manual
2
#1
2 Network switch (with optional
redundant power supply)
4 DCNM-PS2
Bosch Security Systems B.V.
DICENTIS