Packet Analyser Operation

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Summary: A packet analyser allows real time monitoring of the data stream on the power bus.

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DCC Meter / Packet Analyzer

This article demonstrates the operation and various output formats available from the NCE DCC Meter/Analyzer.



The device has several connections.

  1. Track Power In
  2. Track Power Out
  3. USB B port

Terminal blocks are supplied to allow easy insertion of the device. Wires are connected to the terminals, which are then mated with the correct connector on the device.

The meter is a flow through device, power is supplied by the track outputs on the booster, and the meter's output is connected to the track bus.

When track power is present it displays Volts and Amps.

A button toggles between the meter and analyzer modes.

Data Monitoring

To monitor data in the Analyser mode, a button below the display toggles between modes. When in this mode the display indicates it is now operating as the analyzer.

A terminal is connected via the USB port. A computer running a terminal program allows control and display of the data stream.

Modes and Commands

Note: There is an error in the printed manual regarding the Hexadecimal modes. The available modes are H0 and H1.

  • H0: Only packet payload bytes are shown, with a space between each byte.
  • H1: The Preamble and the number of bits are shown, followed by address and data bytes.
NCE DCC Meter and Analyser
Available Commands
Display Modes
V Display packets in 'verbose' mode
H0 Hex display mode 0
H1 Hex display mode 1
A+ Display all accessory packets
A- Don't display accessory packets
I+ Display all idle packets
I- Don't display idle packets
L+ Display all loco packets
L- Don't display loco packets
R+ Display all reset packets
R- Don't display reset packets
S+ Display all signal packets
S- Don't display signal packets
? Display list of commands supported
In normal operation space bar pauses/resumes display and LCD will display -- USB STOPPED --
Any packet that isn't decoded by the analyzer will be displayed in hex
Reset packets will be displayed as: RESET
Idle packets are displayed as: IDLE


Verbose Mode

NCE DCC Analyser
Verbose Mode
Locomotive, Address Speed and Direction Function Group Active
L2499 S000F
L2499 FG1 00,01,,03,04
L1600 FG1 00,01,,,04
L2499 FG2 ,05,06,07,08
L1600 FG2 ,,,07,08
L2499 FG3 ,09,,,
L1600 FG3 ,,,11,
L2499 FG4 ,,,,,,,,
L1600 FG4 ,,,,,,,,
L2499 FG5 ,,,,,,,,
L1600 FG5 ,,,,,,,,

The speed is displayed as the number of steps (0 – 127) and the direction. If the multifunction decoder were operating in 14 or 28 step mode the display and values would change accordingly.

Functions are displayed as to which group they are part of, and their status. When not shown, the function is inactive.

Hexadecimal Modes

H0 Mode
NCE Analyser
H0 Mode (Hexadecimal Output)
Address Payload
C6 40 A4 22
C9 C3 3F 80 B5
C6 40 3F 80 39
C9 C3 DE 00 D4
C6 40 DE 00 58
C9 C3 DF 00 D5
C6 40 DF 00 59
C9 C3 BF B5
C6 40 BC 3A
H1 Extended Output

This mode prepends the Preamble, indicated by the letter P, and its value.

The example shows the preamble has 15 bits, one more than the nominal value of 14. This is useful for diagnosing issues such as data corruption or RailCom, as a multifunction decoder requires a minimum of 10 bits, and no more than 12 for proper operation.

NCE Analyser
H1 Mode (Hexadecimal, Extended)
Preamble Payload
Extended Address Data
P0F C9 C3 9D 97
15 (decimal} 195 201 157 151
1111 (binary) 1100 0011 1100 1001 1001 1101 1001 0111
P0F C6 40 99 1F
15 197 197 197 197
P0F C9 C3 3F 80 B5
P0F C6 40 3F 80 39