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Each block must have a means of detecting occupancy. The BD20 manufactured by NCE is a simple and effective block detector. Three BD20s are recommended. As the blocks get longer it is better to have another detector in the following section of track to sense when the engine has entered that block. As described at the end of this document it is possible to use less than 3 detectors.
Connecting each BD20 to the NCE Command Station is accomplished with the AIU (Auxiliary Input Unit) manufactured by NCE as well. The AIU needs to be connected with the cab bus. Once the AIU is connected into the cab bus, and thus into the Command Station, DecoderPro does the rest.
The track used must be connected to the mainline from the NCE system. Do NOT connect it to the programming tracking wiring.
The choice of track is up to the user and the space available. An independent section of track or a long siding on an existing layout are both acceptable. The independent section of track can be long and straight or it can be a loop. Each type has their advantages and disadvantages.
It is also possible to use this Speedometer while the rest of the layout is operating. If you do, make sure you are not blocking the mainline or at least have the proper authorization from the dispatcher.
Figure 1 shows the ideal setup for connecting the block detectors into the NCE system with the BD20s and AIU.
Figure 1 shows how to integrate the sections of track, block detectors and AIU into the Command Station.
Make sure there is a good solder connection between the wire and the rail and that the rails are clean. It is possible to have false readings on the speedometer if the DCC signal is interrupted.
It is only necessary to put gaps into one of the rails. It does not matter which rail is gapped.
You can use a loop of track or a straight section of track. For a loop, block 5 in the diagram is connected to block 1 and the power feed to block 5 can be removed since it is powered in block 1.
The BD20s should be located within a reasonable distance from the track.
The wire at each block should be soldered as close to the start of the block as possible.
Follow instructions for the BD-20 regarding number of turns.
Follow the instructions for the AIU as well. As the AIU instructions state, it is a good idea to change the default cab address from 4.
All of the wires from each pin 1 of the BD20 must go to GND pin on the AIU. The wires from each pin 2 on the BD20 goes to a unique pin on the AIU.
Sensor ID = (AIU Cab Address - 1) * 16 -1 + (Pin Number On AIU)
For example: The AIU cab address is set to 50 and one of the BD20s is connected to pin 2. Therefore the Sensor ID would be:
Sensor ID = (50 - 1) * 16 -1 + (2)>
Sensor ID = 785
Red: No reading, status unknown (typically if no value for the sensor ID is entered)
Yellow: Block occupied
Green: Block unoccupied
Distances 1 and 2 both start at the beginning of block 2 (or the end of block 1).
For metric units press the 'To Metric Units' button and enter the information in the correct units.
Now that everything is hooked up and the speedometer form is open and the correct values entered as required we are ready to use the speedometer.
If you have a loop, once the train has reached block 5 (actually the beginning of block 1) stop the train as well before it reaches the end of block 1. If you don't the timer will restart.
Obviously the primary use for the Speedometer is to create custom speed tables. Creating speed tables can be used so different types of engines can run together as a consist.
Everyone's method for implementing a speed table may be different. But as a starting point here is some general guide lines.
Now is the time to match the other engine. This is where programming on the mainline is the only way to go. At each speed step document the speed of the engine.
The engine should now perform as the template engine.
Back to the Speedometer main Help page.