Multi-unit lashup

Proposed Standard
Aaron Gonthier wrote 22 August 2019:


 * I am working on a standard for locomotive control wiring for battery electric locomotives. It uses a premade Ethernet cable to go from the motor controller (or other control device) to the handheld throttle. The purpose of the standard is to make it easy to change out a broken cable or swap handheld throttles, cables and controllers from one locomotive to another with a minimum amount of rewiring. Ethernet cables are available most places in North America, from big box stores to convenience stores. They work with analog or digital control systems and allow for basic controls and a minimal amount of electronics in the handheld throttle.


 * Having only the essential controls simplifies wiring, with only throttle, forward/reverse, horn and optional brake controls. Lighting controls can be on the locomotive or integrated with the reverser controls using a relay on the locomotive.


 * My hope with this proposed standard is to make it a little easier for people building and maintaining battery electric locomotives. Your input is appreciated.


 * Aaron Gonthier
 * Mill Brook Railroad
 * Windsor, VT

Editor: Please note the pinout below is modified from Mr. Gonthier's initial description.

Description

 * Two Multi-unit lashup cables are defined. Connector #1 is required, Connector #2 is optional.
 * All signals range from 0 volts D.C. (ground) to 12 volts D.C., +/-10%
 * The signals use "positive logic" (e.g. 12 volts D.C. indicates the signal is active)
 * Units (locomotives) are to provide RJ-45 sockets on both ends for Connector #1, and an optional second RJ-45 connector on both ends for Connector #2
 * Every signal is carried through the locomotive from front to back and, unless otherwise noted, are not modified by the locomotive
 * Signal voltages may need to be converted to different logic levels on each locomotive
 * Up to four units may be joined together without further signal amplification
 * The source generating each signal must supply a minimum of 100 milliamps for 0 and 12 volts D.C.
 * Each unit must consume no more than 20 milliamps from a given signal. This is sufficient for driving the coil of one automotive relay in each unit.

Connector #1

 * Pin 1. 12 volts D.C. (Signal high) - white/orange
 * Pin 2. Brake Release (optional) - orange/white
 * Pin 3. Forward - white/green
 * Pin 4. Ground (Signal Low) - blue/white
 * Pin 5. Horn - white/blue
 * Pin 6. Reverse - green/white
 * Pin 7. Brake Apply (optional) - white/brown
 * Pin 8. Speed - brown/white

Notes:

a. Each unit provides 12 volts D.C. to Pin 1 through a 5 amp fuse and an appropriate diode, such as a 1N5400, to prevent reverse current to the unit's battery. Each unit provides a minimum of 1 amp.

d. Pin 8 provides speed information to the drive motor of each unit. A signal of 0 volts D.C. (ground) results in no power to the drive motor. A signal of 12 volts D.C. results in maximum power to the drive motor. A variable voltage on Pin 8 between these two values will adjust output power to the drive motor accordingly. Some drive controllers, such as the Syren-50, require a 5 volt D.C. maximum input, so signal conditioning may be required on each unit. Units may not alter the signal on the bus. An eight notch throttle can be simulated by providing the following voltages to Pin 8:
 * 0.0 volts - No power to drive motor (idle)
 * 1.5 volts - Notch 1
 * 3.0 volts - Notch 2
 * 4.5 volts - Notch 3
 * 6.0 volts - Notch 4
 * 7.5 volts - Notch 5
 * 9.0 volts - Notch 6
 * 10.5 volts - Notch 7
 * 12.0 volts - Notch 8

Connector #2 (Optional)

 * Pin 1. 12V (Signal high) - white/orange
 * Pin 2. Headlight High Beam - orange/white
 * Pin 3. Headlight Low Beam - white/green
 * Pin 4. Ground (Signal Low) - blue/white
 * Pin 5. Bell - white/blue
 * Pin 6. Air Compressor - green/white
 * Pin 7. Number Board Lights - white/brown
 * Pin 8. Step Lights - brown/white

Notes:

a. Each unit provides 12 volts D.C. to Pin 1 through a 5 amp fuse and an appropriate diode, such as a 1N5400, to prevent reverse current to the unit's battery. Each unit provides a minimum of 1 amp.

c. When Air compressor signal is active (12 volts) each locomotive may turn on its own compressor. A locomotive may optionally enable the Air compressor signal (e.g. if it detects low air pressure), through a 5 amp fuse and an appropriate diode, such as a 1N5400, to prevent reverse current to the locomotive's battery.