Model Railroad Control – an initial shopping list

Before we can start exploring model railroad control, we’ll have to do some shopping. This is what I got and why.

NS 2200 class locomotive, VAM wagon, track, z21 DCC system, Multimaus throttle. All from Roco.
NS 2200 class locomotive, VAM wagon, track, z21 DCC system, Multimaus throttle. All from Roco.


My starting point with automated model railroad control was… a model railroad with the capability to automate. What is necessary to get started:

  1.  Locomotive with a DCC decoder – we need something to control of course
  2. At least one wagon – a locomotive without any wagons is hardly a train
  3. A few pieces of railroad track – the train has to roll on something, provide the train with power and a communication channel with the command station
  4. DCC command station – the main control center for the train
  5. Booster – something that boosts the (weak) DCC signal to a stronger signal that can actually power a number of trains
  6. Power Supply – not to be underestimated: if multiple trains need to run on a large layout, a lot of power is needed. Since the voltage is in the range of 18v, this means quite a large current (ampere).
  7. Throttle – a user interface to send commands intended for trains or switches to the command station
  8. Computer Interface – something that enables the computer to communicate with the command station.

Extra personal requirements that are not necessary for automation:

  1. A Dutch theme in the early 1980’s (also called era 4) – for nostalgic reasons
  2. H0 (1:87) scale – because of the largest availability of rolling stock and the balance between size of the rolling stock and area needed for a legitimate model railroad.

When I look at the availability of model trains in brick and mortar shops in Sweden (where I live), Märklin is  clearly the dominant force. Märklin also has a number of interesting Dutch models in its catalog. However, when it comes to automation, it uses a proprietary MFX protocol rather than DCC and is hence disqualified.

The next largest is Roco (especially after it acquired Fleishmann). This brand uses DCC and also still has quite a few interesting Dutch models. It seems like the quality of the modern models is not worse (in terms of technical properties and also level of detail) than Märklin, which is a nice bonus.

Roco starter set

Initially, I bought a Roco starter set which included:

  1. Roco locomotive – a Dutch class 2200 model with inbuilt DCC decoder
  2. A few Dutch wagons of questionable quality (I bought a few better wagons separately afterwards)
  3. A few pieces of Roco geoLine track to build an oval layout
  4. Roco Multimaus – A very nice throttle that can also can act as a Control Center together with the Digital Amplifier (in Master mode)
  5. Roco Digital Amplifier (10764) – A proprietary and very simple DCC booster that only works with the Multimaus (in Master mode) and can accept a secondary Multimaus (in Slave mode)
  6. A suitable power supply for the Digital Amplifier.

This Digital Amplifier has no specific computer interface. My hope was to create an interface that could emulate a Multimaus in slave mode and connect the computer to this amplifier. It turns out that a Roco chose the XPressNet protocol for communication between throttles and control center.

XPressNet builds on the serial multipoint RS485 serial interface between throttles and the control center. This protocol is primarily used in industrial settings and the choice for this protocol is very elegant. But unlike RS232 which is a point-to-point serial interface and still cheap widely available as an USB to RS232 dongle, an RS485 interface is much harder to come by. One could purchase such an interface from Lenz (expensive) or build one, for example using an Arduino micro controller.

While I have an Arduino laying on the shelf somewhere, I’m not a hardware person so I don’t feel tempted to go this road. And buying an expensive interface would go beyond the scope of my explorations. Combined with the fact that the Digital Amplifier is limited in other ways, I abandoned this option.

Z21 black and white

In the mean time, Roco abandoned this Digital Amplifier as well, and started packing a new product in its digital starter sets: a z21 command station and booster, with a wireless access point and matching power supplies. Roco made free throttle apps available for smartphones and tablets (Android and iOS) and stopped including a Multimaus in the starter sets. The Multimaus can still be connected though, it will run in slave mode then.

Ironically, Roco chose to include the (white) z21 in starter sets only, and make a more advanced (black) version called Z21 available for purchase separately. The irony is that the Z21 is incredibly expensive and not needed for most people.  Since the market demand is primarily for the limited z21, many shops decided to ‘gut’ the starter sets and sell the individual components for a relative bargain. The advantage for these shops is that they still make more profit for the discounted components than for the complete starter sets. The advantage for the market (i.e. me) was that I could get my hand on a z21 command station/booster, wireless access point and power supply relatively cheaply.

At the time of writing, Roco includes a z21 together with a Multimaus in its starter sets. However, they limited the z21 in terms of  a ‘start’ edition. The limitation is in the disabled network interface: this has to be purchased separately. One can choose to only buy an activation code, or an activation code together with a preconfigured WiFi base station.

I still could buy or build an XPressNet interface and connect it to one of the x-bus sockets just like the Multimaus. However the interesting thing about the z21 or Z21 for our explorations is this network interface. Jjust like Rocos throttle apps, one can connect their computer using this interface, either wired or wireless (via the WiFi base station). Roco published the API (Application Programming Interface) and since that means software only, we’re going to use that for our further explorations!