A house number for each decoder


Are your heads still spinning from last time when we introduced a new number system with just two different numbers? As humans we normally prefer the decimal system with 10 different basic numbers ranging from 0 to 9. If only 2 numbers are differentiated, we talk about a binary system.
If you only know two different numbers, these can also be depicted by the different conditions "on" and "off". If the power is switched off, this corresponds to the number 0, while the number 1 stands for power on. This is a domain of a computer which is very well capable of generating, transmitting and analysing these two conditions and therefore carrying out calculations based on this binary number system.

In order let our digital control switch a point, the decoder needs to know, whether it is addressed and what command it has to implement. Therefore, firstly, the main information is the address that needs to fulfil some requirements:

1. In order for the desired decoder to react, its address must only be assigned once. If 2 decoders have the same address, they will always implement the transmitted commands together. There might be special cases where that is useful. However, the normal condition is that this address is only assigned once.

2. Modern digital systems feature different transmission formats. These are referred to as MM (abbreviation for Märklin Motorola format) or DCC (abbreviation for Digital Command Control). Both systems use addresses, of course. Therefore, the decoder needs to know to which of the two systems it is supposed to react.

3. The address range should be sufficient for the task. The Mobile Station distinguishes up to 320 addresses for switches and signals. Here one may say that the model railway enthusiast will hardly reach this limit. Even if you already plan a huge model railway layout in your dreams.

In principle, there are two different types of turnout decoders. The installation decoder 74461 or the multi-way decoder 60832, where you can connect up to 4 turnouts. Let's first start with addressing the installation decoder 74461. This decoder is installed below into a C-track turnout. When you look at a turnout with installed decoder 74461 from below you can see a switch panel with 10 different switches. 9 of these switches named with the number 1 to 9 serve for setting up the address. The tenth switch in the rightmost position, has the number "0" and servers for setting up the operating system. For this decoder can understand either the MM or the DCC format. If this 10th switch is in the down position "off", the decoder reacts to the MM format. In technical language, this position is also referred to as "off" position. You may surely know this term from many other technical devices. However, if this 10th switch is in "on" position, our decoder will only react to the commands in DCC format. 

Important: The Mobile Station no. 60657 requires us to decide for one of the two systems. All turnout decoders react to either the MM or the DCC format. In the case of the CS 3, however, one has the possibility to decide for each decoder separately whether it is controlled using the MM or the DCC format.

By the way, during operation, there are no significant differences when using the MM or the DCC format. For example, if you have even older decoders that can only be controlled using one of the two formats, of course you have to opt for that format. The MS 2 features the MM format as the factory setting. Therefore, it is no wonder, that this is in practice most frequently used with Märklin layouts.

When entering the address on the nine other switched you have to consider a special feature. In the decimal system we are used to the fact that the units are at the rightmost position and the tens digit is left of it, then, one digit further to the left, there comes the hundreds digit. Therefore, for us the number 435 means 4 x 100 + 3 x 10 + 5 x 1.
However, in Mathematics, this system also exists with the binary system. In the case of the coding switches, however, the units digit is in the leftmost position, the tens digit is right of it, and so on. So, the address "1" is not set as 0 0 0 0 0 0 0 0 1, but in reverse order as 1 0 0 0 0 0 0 0 0. Therefore, these are the positions of the coding switches for the first 10 addresses:

You might have possibly noted, that we haven't listed the address "0", where all switches are in "off" position. This address is neither used for the DDC nor the MM format. Therefore, in practice, this coding position doesn't make sense. In the next issue we will have a look at how to program the universal module. And of course, we don't want to withhold further suggestions on assigning addresses from you. Until then, have fun with your Märklin model railway.