Optimising the CVs for a further update to the Zimo decoder software for the pair of DRS Bachmann Class 57/0 locomotives

 

Introduction:

This page describes the configuration used to customise the latest version of Paul Chetter's Class 57 Sound Project for Digitrains.

Power step transitions come in three options, to suit small, medium or large layouts (programmable via CV265).

The new software will be available from Digitrains as "Digidrive E Class 57"

Class 57/0 at York station in 2008.

 

The planned lighting controls:

(1) Normal directional light engine lighting via button zero.

(2) Directional lights at end one only, via button 20.

(3) Directional lights at end two only, via button 21.

(4) Cab light at end 1 (the only manned cab) via button 8.

(5) Connector at end 2 to enable some (dubious) effects in the front nuclear flask carrier, enabled via button 10.

 

A Table Summarising the proposed mapping changes:

Function Button

As Received Mapping Changes
0F & 0R Directional Lighting 0F= FO0F + FO2   0R= FO1 + FO0R
1 Engine start/stop Engine start/stop
2 3 Tone Horn 3 Tone Horn
3 Single tone Horn Replace with 2 Tone Hi-Lo horn
4 Brake release Brake release
5 Air brake activation Air brake activation
6 Reduce engine sound to idle Reduce engine sound to idle
7 Engine compressor  Engine compressor
8 Reserved for cab light Assign to FO4  
9 Wheel Flange Squeal Wheel Flange Squeal
10 Primer pump   Assign to FO3.  Number 1 Class 57: Vacant        Number 2 Class 57: End 2 External Connector    (pulse 100ms off, 100ms on)   remove sound
11 Blower Blower
12 Brake squeal (on rails) Brake squeal (on rails)
13 Door slam Door slam (with volume reduced )
14 Spirax Valve Spirax Valve
15 Metal clang ? Metal clang ?
16 Failed engine start sequence Failed engine start sequence
17 Single tone horn (more prominent than 3) Single tone horn
18 2 Tone Hi-Lo Horn Zero CV3 & 4     remove sound
19   Shunt mode
20   End 1 lights via Swiss mapping
21   End 2 lights via Swiss mapping

The areas in pink require change action

 

Sound changes require a view of the mapping used within the decoder:

line 1: Brake release, 3 tone horn, single tone toot, better single toot, 2 tone Hi-Lo horn.

line 2: Putt-putt blower.

line 3: Metallic clank.

line 4: Air Brake activation, failed engine start, primer pump, spirax valves, door slam, wheel flange squeal, compressor.

line 5: Brake squeal (on rails).

line 6: All the engine sound clips............

 

Sound Adjustments: (Via POM)

CV Function Key Remove Add
300 3 Single Horn 2 Tone Hi-Lo Horn
300 18 2 Tone Hi-Lo Horn -
300 10 Primer pump -
300 13 - Door slam reduce volume

 

The  CV updates:

Description

CV Number

Old value

New value 57011

New value 57012

Master volume

266

64

16

16

Power transition point mode 265 101 103 103

Add shunt & Zero momentum

124

0

3

3

Shunt mode to button 19

155

0

19

19

Zero momentum to button 18

156

0

18

18

Bemf sampling rate & period to smooth out step2/28

9

0

87

87

Start voltage

2

1

OK OK

Accel delay

3

45

OK OK

Decel delay

4

25

20 20

Max speed

5

1

OK OK

Half speed

6

1

OK OK

Bemf feedback (speed) setting

57

90

130

130

Check mapping regime

61

97

OK

OK

Check SW issue

7

32

OK

OK

 

 

 

 

 
Light engine fwd 33 1 1+8=9 9
Light engine Rev 34 2 2+4=6 6
 

 

 

 

 

Cab light Aux4  to  F(8)    

42

 

32

32

Aux3  to  F(10)      TBA

44

32

16

16

Flash waveform timing set to 100ms on & 100ms off

117

0

0

0 (=00)

Assign flash waveform to Aux3 output

118

0

0

16

Address (temporary, for consist testing)

1

3

4

3
         
Reset F(9) to zero 43 16 0 0
Reset F(11) to zero 45 64 0 0
Reset F(12) to zero 46 128 0 0
         
Swiss mapping end 1 lights only 430 0 20 20
  431 0 157 157
  432 0 14 14
  433 0 0 0
  434 0 15 15
  435 0 0 0
Swiss mapping end 2 lights only 436 0 21 21
  437 0 157 157
  438 0 2 2
  439 0 0 0
  440 0 1 1
  441 0 0 0

 

 

Driving characteristics of the new software:

Three sets of engine notch transition speeds are provided, to enable all the engine power levels to be exercised on different sized layouts.

In reality, the engine power required in a diesel electric locomotive, depends on the effort required to move the train at the speed in use. A lightly loaded locomotive may well be cruising with the engine at idle speed for long periods, while a locomotive pulling a heavy train may need full power just to get the train moving from a standing start. Add some track gradients to a loaded train and the relationship between locomotive power level and speed is not at all constant. The 3 operating modes can be selected using CV265:  Value 101 gives power transitions up to maximum over the lowest  speed range (targeting smaller layouts). 102 moves the transitions a little higher in speed, while 103 caters for larger layouts, typically with a continuous loop.

Paul Chetter has influenced Zimo to include the F6 function, enabling the locomotive to be dropped to idle power from any starting point, to more correctly simulate actual driving practice during cruise periods and in particular, before a train is brought to a halt.  Additionally, although the upwards power level transition speed steps are fixed within each of the three layout related options, the power level can quickly be dropped to the next level down by a single power step reduction (which on a 128 speed step system has virtually no visible effect on locomotive speed.) So with practice, prototypical engine power levels can be achieved more often than not.

 

 

Running a 57 with the latest Zimo software under computer control:

A brief trip is taken up and down the test track with one of the KUA 16 wheel Royal Navy nuclear flask carriers hooked up to the number two DRS Class 57.

Zimo fitted Class 57 with the latest KUA update in tow. With only a centimetre or so to spare, stopping locations are critical on the small test track.

 

The two 57s double heading in consist on the test track.

 

Use this link to watch the DRS Class 57 pair & KUA (set to layout size option 3) on YouTube: Click here.

 

 

Supplier website links:

 

Rails of Sheffield    The Class 57 units above were originally purchased from this excellent e-shop.
Digitrains    Helpful source for the Zimo sound decoder and ESU speaker.
Zimo Website    For access to the user manuals and newsletter programming updates
Rapid Electronics of Colchester    A good reasonably priced source for electronic components.

 

The photos of the models were taken using a hand held Canon Ixus 220.     The photos of the real 57012 loco were taken back in 2008 at York Station.

 

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