All connections of the black Z21

Main Track

● 3 A
● Short circuit detection
● Track voltage can be adjusted from 12 to 24 V
● Setting via Z21 app and Z21 Maintenance Tool
● Maximum track voltage = 1 V below input voltage

2 Rails DCC


DCC Loco-Decoder

  • 14/28/128 speed steps
  • F0 to F28
  • POM read nbsp#write


DCC Turnout- and Signal-Decoder

  • Configuration of sophisticated decoder 
  • 2048 DCC-turnouts 

3 Rails MM


MMI and MMII Loco-Decoder

  • MMI: Address 1 to 80 and 14 speed steps
  • MMII: Addresse 1 to 255 and 28 speed steps


MM Turnout-Decoder

  • 255 MM turnouts possible

Please note: The polarity when connecting 3-rail tracks and MM turnout decoders! Some MM turnout decoders must be connected with proper polarity in order to process the MM signal correctly 


Prog Track - Programming track

  • CV Programming
    According NMRA S-9.2.3
    Reading/writing CV bit- and byte-wise 
    In direct mode
  • MM Programming
    6021 programming mode
    Z21 FW V1.23 or higher
  • Decoder Update
    with Z21 Maintenance Tool
Hint: CV programming can be cancelled by shortly pessing the STOP key

LED Status

Constant blue - Normal operation

Lit in green - Programming mode

Flashing green - Decoder update

Flashing blue - STOP

Flashing red - Short circuit

Sniffer BUS

Driving and switching by using your existing legacy DCC digital command station (output voltage of 16 V or higher required).


At any time you can take over the loco with another throttle (or App) connected to the Z21.


The direction of communication is always from the legacy command station → into the Z21.


Booster BUS

10789 - Z21-CDE Booster Adapter

10-15 Booster with CDE interface

10765 - Digital Booster 

Up to 3.2 A per booster
With five and over, you need the brake generator 10779

LocoNet™ BUS

1. Currently supports more than 21 tested hand controllers and feedback modules of a wide range of manufacturers: 

Z21 FW V1.24 or higher

LocoNet T (Master) 12 VDC, 500 mA


Profi-BOSS as LocoNet™ Slave






Funkmaster update

IRIS + 63830 IR-Receiver



TWIN-CENTER, Intellibox 1, TWIN-CONTROL, IB-Control

LocoNet™ Slave






Automation using IR


Automation using IR


Power supply

63400, 63410

Input/output module

Blücher GBM16XL

Occupancy detector

Blücher GBM16N

LocoNet™ Interface

Occupancy detector

Train detection using RailCom®

63320, 63340

Occupancy detector (2-rail tracks)


Following modules are not compatible with the Z21:

  • LocoNet™ Booster
  • BDL168, RX4
    Occupancy detector using transponding


Following modules are not compatible with full bridge power circuits and must not be connected to Z21 or Digitrax command stations:

  • MARCo
  • 63330, 63350
  • 68720, 68730

TWIN-CENTER: Slave mode with FW V2.000 via special option 844 = 1

Intellibox 1: Slave mode with FW V2.001 via special option 844 = 2

(i. e. LocoNet™ power source = off)


Activating LocoNet™ slave mode on PROFI-BOSS:

1. C + alt
2. Change MASTER to SLAVE 
3. Confirm


* Take over a loco address by using dispatch procedure in Z21 Maintenance or Z21 app

The L-BUS also permits connection via a multiZENTRALEpro to the multiMAUSpro

2. L-BUS enables the connection to multiMAUSpro via multiZENTRALEpro


Z21 FW V1.24 or higher with Z21 as LocoNet master



FW V1.09 (LocoNet™ slave)



Connect to EXT. 

The multiZENTRALEpro is the LocoNet™ slave and is powered by ther Z21 (12 VDC).

So do not use any power supply for the multiZENTRALEpro!

Connect the tracks with the LocoNet™ master.

4. With Z21 FW V1.22 or higher, the Z21 can be configured as LocoNet™ slave by using the Z21 Maintenance Tool 

Control the locos of your TWIN-CENTER/Intellibox 1 by using the Z21 app, Z21 multiMAUS etc...

This digital command station is the LocoNet™ master. In this use case, the Z21 is used as gateway between the TWIN-CENTER/Intellibox 1 and all the Z21-throttles or Z21 apps.

It is now possible to control your layout not only with the TWIN-CENTER/Intellibox 1 and its LocoNet™ throttles, but also with the Z21 app on the smartphone/tablet and Z21 multiMAUS at the same time.


In order to avoid that the Z21 and the existing LocoNet™ master both provide the supply voltage at the same time, the supply voltage must be isolated on the L-BUS-connector (pin1 and pin6) at the Z21.

In order to do so, please solely use the white "Z21 LocoNet™ Slave cable" with the spare part number 136100. 

Please ask your local dealer or find it online here

Using the wrong cable can damage the digital control unit!


Z21 multiMAUS firmware update and language change by using Z21 Maintenance

Feedback module (e. g. 10787) for momentary or permanent contacts

20 modules with ascending adresses

8 inputs per feedback module

  • Combinable with circuit tracks (e. g. 61117, 42518 ...)
  • Combinable with sleeper with built-in reed switch (e. g. 42605, 61193 ...)

Blücher GBM16XN

XpressNet™ Interface

GBM FW V1.11.2 or higher


31 devices can be connected to the X-BUS of the Z21.
Including the following:



Route Control

Lenz LH100

Lenz LH30

Lenz LH90 - Z21 FW V1.24 or higher

Funky - Z21 FW V1.24 or higher

Blücher GBM16XN (Occupancy detector for PC-automation Rocrail, iTrain...)

XpressNet™ Interface

Z21 FW V1.24 or higher
GBM FW V1.11.2 or higher


LAN mobile

Connection to the following programmes

Z21 app (Previous version)


Connection to following programmes


Zimo MX32

Z21 FW V1.25 or higher and Zimo FW V01.15 

CdB electronics

CdB electronics
Switching decoder

CdB electronics
Feedback decoder

CdB electronics
Track diagram control panel

CdB electronics
CAN control panel