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Model Railroad Control Systems

cpNode Version 2.7


cpNode Version 2.7

4.00 LBS
Calculated at checkout

Product Description

cpNode and I/O expander (IOX) boards have been updated to version 2.7. Based on customer feedback, and our design and installation experience, the changes were made to provide more efficient and flexible physical layout of some components.  For new systems, see cpNode-ProMini.

 Rev 2.7 boards are 100% backward compatible with current versions. No software changes are needed.

Version 2.7 brings the following improvements to the proven cpNode design:

  • CMRInet interface connection has been made consistent with five position pads (R+, R-,T+,T-,SHLD).for 3.5mm screw terminals, we've removed some rarely used configurations
  • Input/Output pads moved .2" back from edge for better DIN rail clearance. The I/O option pad area accepts standard DIP component headers with 0.4" pad spacing.
  • Gnd/LED Com pads aligned to .1" (2.54 mm) for a screw terminal block or male header pins
  • added option for 4 x 6 position screw terminals each with 4 i/o +5 and GND.

What does a cpNode do?

cpNodes provide input and output (I/O) ports which connect to LEDs for signals, push buttons, turnout motors, block detectors, and other devices to a central computer for controlling model railroads.  cpNodes may also be used as standalone controllers for staging, crossings and interlocking plants.

  • You must provide a  processor, (BB-ProMini or the now-discontinued BB-Leo), we have other processor options in development.
A cpNode has:
  • 16 I/O lines with solder pads for LED limiting resistors
  • Screw terminal blocks or solder pads to connect external devices - see configurations below
  • CMRInet RS-422/485 Network Interface.  CMRInet is now NMRA Layout Control Specification S9-10
  • I2C interface for adding Input/Output Expander (IOX) boards for more i/o ports
  • All the i/o needed to control one end of a CTC siding, just add signals and detectors and switch motor drivers
  • Female headers to receive a BB footprint processor (BB-Promini or BB-Leo) to order with the BB-ProMini use option cpNode with BBPM
  • I/O is configured in 8 bit groups, providing up to 144 lines when fully expanded with IOX16s and/or IOX32s
  • Use cpNodes as small, economical, CMRI nodes as is or customize the code to support applications requiring local intelligence
  • Standard "Sketch" (Arduino program) is compatible with JMRI or traditional CMRI BASIC/Visual Basic development tools


  • The default configuration (AT) has screw terminals installed for the CMRInet and 0.100 screw terminals for the i/o, most users will want this option
  • The No Header (NH) option has screw terminals installed for the CMRInet and no i/o connectors so the user can install his 0.100 connectors of choice contact us for a quote if you want custom assembly with your favorite connector)
  • BB-ProMini (PM) Configuration is the default (AT) configuration with a BB Pro-Mini (BB-Leo has been discontinued by the manufacturer) installed. This is ideal for customers desiring a single source, especially international customers wanting to consolidate shipping.

If you need a configuration which isn't listed, please contact us and we will be happy to quote you on a custom configuration

 Use the Bare Board Option if you want to assemble your own or contact us for a custom quote for an Assembled and Tested unit using your favorite connector.

From time to time we have used cpNodes as a result of system reconfiguration, down-sizing or dismantling of layouts, these items are listed under options. Unless otherwise noted they are in good condition and and can be expected to give years of reliable service.

cpNode sketch for free-standing tower (no CMRINet)



Configuration Instructions


Technical Guide

cpNode Schematic

cpNode Instructions

cpNode Build BOM

cpNode Kernel sketch for BB-Leo

New Sketch for BB-ProMini

cpNode 2.6 EAGLE files


Product Reviews

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