Roco Z21

Z21/z21 Firmware


  • Track power voltage, load and CS temp. in status bar.
  • Track power On/Off
  • System status
  • Programming track and POM
  • Running DCC locos with 14, 28 and 127 steps
  • MM support for addresses < 256
  • 28 Loco functions
  • Switch/Output commands
  • Timed switch commands for coils¹
  • Sensor report evaluation
  • Switch report evaluation
  • Loco report evaluation
  • Watchdog to keep the connection alive after 30 seconds of idle time.
  • Programming RMBus
  • CAN Z21 10808 detector support

¹) Commands for the same address are rejected in case the timer did not yet elapsed.



Factory default is which is also used if left empty.


Default is 21105 if left to zero.


This option is needed for getting (speed, direction and function) info events from the Command Station of manually1) controlled locos to synchronize Rocrail clients.
Without this option the subscription on loco info is done individually for each loco after a speed or function command is send from Rocrail.

Use same sensor bus

Use bus 1 for both LocoNet Input and LocoNet Multi Sense events.

Program FB

z21-10787.jpg Program a Roco 10787 sensor module.

  1. Read the 10787 manual.
  2. Make sure only one sensor module is connected to the RMBus.
  3. Fill in the wanted address and push the “Program FB” button.
  4. :!: Program address zero after the sensor module has acknowledged.



Bus Network Z21 Firmware
0 DCC 1.0
1 Loconet 1.2
2 CAN ?

Switches, outputs and signals do only use the address field.


Bus Network Z21 Firmware Remark
0 R-Bus 1.0
1 LocoNet Input 1.2 LocoIO, DR5088RC(Feedback)
22) LocoNet Multi Sense 1.2 GBM16XN, DR5088RC(Block)
3 CAN 1.29 Roco Z21 CAN Detector

Flat addressing

Module 1 → Address range 1-8
Module 2 → Address range 9-16

Special Feature

In the default setting of the z21 / Z21 there is an address offset of +4 between Multimaus and Rocrail. This means that in Rocrail the addresses 1-4 can not be used. If e.g. address 1 of the multimouse is to be used in Rocrail address 5. But there is an elegant way to eliminate this shift. To do this, connect the z21 to the computer via the z21-maintenance-tool, activate the option “DCC-switch address shift +4” on the “Settings” tab and then confirm with “Write”. Then the addresses from 1 can also be used in Rocrail. Addressing is done exclusively according to FADA (flat addressing).

Rocrail & GBM16XN

Trouble Shooting


eth-switch.jpg The Z21 cannot access the LAN when connected to an 'old' Ethernet HUB.
The easiest way to get connected is to add a small Desktop Ethernet Switch between the 'old' HUB and the Z21. (Small Switches are available for less then €10.)


The z21start has a restricted network interface which does not accept commands from Rocrail or other software.
To use the z21start with Rocrail an Unlock-Code (10818) or an complete z21 WLAN Package (10814) must be installed.


1) External throttle
2) See the “Use same sensor bus” option.

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