What a blockhead… assigning addresses to the LDT RS-8 in JMRI

Maybe I’m just a blockhead, but when it comes to understanding some of the instructions associated with DCC block occupancy (or DCC in general, for that matter), often they’re as clear as mud!

When assigning addresses to blocks on the LDT RS-8 in JMRI, there were really two parts to the story. Part 1: Setting the block addresses of the RS-8 and Part 2: Understanding the block addresses set in JMRI.

JMRI addresses for the RS-8 feedback module applied to blocks on the trackplan
JMRI addresses for the RS-8 feedback module being applied to blocks on the trackplan

Part 1: Setting the addresses of the RS-8
To assign addresses to the blocks controlled by the RS-8 in the first place, I first had to workout how to get the Lenz system to talk to it. This isn’t immediately obvious from the instructions, as these assume you have the Lenz LH100 hand controller. I have the Lenz Compact and LH90 controllers, but the simple answer is that the address is assigned in the same way as you assign addresses to turnout decoders. Just follow the instructions for ‘Switching points and signals’ for the controller you have, but make sure they’re numbered between 65 and 128, which is the range reserved for feedback modules. 1 to 64 is reserved for turnout decoders with feedback function.

The other point to note is that you only have to set the address of the first block (track section), the other seven addresses on the RS-8 are assign sequentially by the module itself. Unlike the Lenz LS150 turnout decoder where you can set the addresses individually, one after the other. The RS-8 comes with the default address of 65, so its addresses would be 65 to 72. So, logically, you would set the address of a second RS-8 to 73 to give a range 73-80, etc.

Re-labelled RS-8 feedback module
Re-labelled RS-8 feedback module

Part 2: Understanding the block addresses set in JMRI
Once I thought I had worked out how to set the block addresses on the RS-8 feedback module, I began to doubt myself. When I tried setting up blocks in JMRI’s ‘PanelPro’ the ‘Sensor table’ was showing block addresses beginning with XS513, where I was expecting to see XS65. In fact, if you look back to the picture of the RS-8 in the post ‘Wiring Wunderland’, I had already labelled the track sections XS69, etc., which is where I was going to start numbering sections from.

Fortunately it didn’t take me too long to track down a reference to this anomaly on the Yahoo – JMRI Users Group, which is essential membership if you are using JMRI. Basically JMRI, as I understand it, allows for eight addresses per module. Meaning that the module at address 1 would give outputs XS1-XS8, module at address 2 would give outputs XS9-XS16, etc. So, by the time you get to 64 (The end of the range allocated to turnout decoders) JMRI is allocating an address of 64 x 8 = 512 (or XS512). Which means that address 65 in JMRI would start with XS513 and end with 65 x 8 = XS520. See what I mean, clear as mud!

Wiring routed from the RS-8 to power separate track blocks
Wiring routed through the RS-8 to power separate track blocks

Re-labeled track block sections
Re-labeled track block sections, to reflect my newly acquired understanding of JMRI’s addressing

PanelPro now indicates occupied track sections
PanelPro now indicates occupied track sections correctly

However, the upshot of all this brain ache is that PanelPro now indicates occupied track sections correctly on the track schematic (apart from turnouts, which I am not detecting) and I wasn’t going completely mad!

I apologise for the lengthy post, but in this case I think less is definitely not more!

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