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 Function-Decoders  MX681, MX685, MX686, MX687, MX688                                                                            Page 15 

CV 

Denomination 

Range 

Default 

Description 

#125

1

 

Special effects 

American lighting effects 

as well as others such 

as uncoupler, smoke 

generator and more 

on  

function output F0 (front 

headlight) 

 

Effects can be further 

adjusted and modified 

with  

CVs #62 - 63 

and 

CV #115, #116  

(for uncoupler). 

 

Bits 1, 0 = 00: bidirectional (active in both directions) 
              = 01: only active in forward direction  
              = 10: only active in reverse direction  

ATTENTION in case of CV #125 and #126: change 
CV’s #33, 34.... if direction is wrong! 

Bits 7, 6, 5, 4, 3, 2   = effect-code   

EXAMPLES  

You want :                                                 Program CV #125 to: 

Mars light 

forward  only  -                                  00000101  =    5   
Gyralite  independent  of  direction    -    00011100  =  28 
Ditch  type  1  left,  only  forward    -        00100101  =  37 

Uncoupler              -                                            00110000  =  48 
Soft start of output      -                             00110100  = 52 
Automatic  stop  light        -                              00111000  =  56 

Automatic  cab  light  OFF  -                              00111100  =  60 
Auto.  smoke  OFF  after  5  min 

–                    01000000  =  64 

Auto.  smoke  OFF  after  10  min 

–                01000100  =  68 

Speed/load  depen.  smoke  -                            01001000  =  72 
Speed/load depen. diesel smoke -               01010000 = 80 

#126 

Special effects for 

rear headlight 

(default F0 reverse) 

 

 

See CV #125 for details. 

#127 - 

#132 

Special effects for 

FO1, FO2, FO3,  

FO4, FO5, FO6 

 

See CV #125 for details 

   #127 

 FO1        #128 

 FO2 

   #129 

 FO3        #130 

 FO4 

   #131 

 FO5        #132 

 FO6 

#159, 

#160 

Special effects for 

FO7, FO8 

 

See CV #125 for details 
   #159 

 FO7        #160 

 FO8 

#62 

Effects modifications 

0 - 9 

Change of minimum dimming value 

#63 

Light effects  

modifications 

or 

Stop light OFF delay 

0 - 99 

 

0 - 255 

51 

Tens digit: sets cycle time (0 - 9, default 5), or start-up  
      time during soft start with 001101 (0 - 0,9s) 

Ones digit: OFF delay time (range: 0 

– 25 sec.). 

For stop light OFF delay (001110xx in CV #125, 126 
or 127): Time in tenths of a second the stop lights re-
main ON after the street car comes to a full stop.  

#64 

Effects modifications 

0 - 9 

Ditch light OFF time modification 

#353 

Automatic  

smoke generator  

shut-down 

0 - 252 

0 - 106 min 

For special effect codes “010010xx” or “010100xx” 
(smoke generator): Overheat protection: turns OFF 
from ½ min 

– about 2 hours. 

= 0: Won’t turn off automatically. 
= 1 … 252: Switches off automatically after 25 sec-
onds/unit. Maximum time therefore is about 6300 sec. 
105 min.   

                                                                            

1

 Note to ditch lights: Ditch lights are only active when headlights and function F2 (#3 on Zimo cab) are on, which is prototypical for North American railroads. The 

ditch lights will only be working if the applicable bits in CV #33 and 34 are on (the definition in CV #125 - 128 in itself is not enough but a necessary addition).  
Example: If ditch lights are defined for F1 and F2, the bits #2 and 3 in CV #33 and 34 have to be set accordingly (i.e. CV # 33 = 13 (00001101), CV #34 = 14 
(00001110). 

3.15  Configuration of Electric Uncouplers  

“System KROIS” and “System ROCO” 

When one or two of the function outputs 

FO1…FO6 

(but not FO7 or FO8) are assigned to the uncou-

pler function (CV #127 for FO1 etc.), the control of the couplers as well as the entire uncoupling pro-
cess is defined by the settings in 

CV #115 and CV #116. 

These CVs limit the pull-in time (to prevent overheating), define a hold-in voltage if required (i.e. Sys-
tem “Roco”) as well as the automated coupler unloading and train disengagement. 

It is recommended to use the following settings for the 

Krois system:

 

CV #115 = 60, 70 or 80; 

these 

settings will limit the pull-in voltage (full track power) to 2, 3 or 4 seconds respectively. A hold-in voltage 
is not re

quired for the Krois coupler and the ones digit can therefore remain at “0”. 

CV 

Denomination 

Range 

Default 

Description 

#115 

Uncoupler control 

 

“Pull-in” time  

and  

“hold” voltage 

or use  

CV # 115  

for an alternative second 

dim value 

0 - 99 

Uncoupler function is only active if “uncoupler” is se-
lected (value 48) in one of the CV’s #125…132: 

Tens digit (0 

– 9): Time in seconds the coupler re-

ceives full voltage (pull-in time):  

Value:                 0       1       2       3        4         5        6        7        8         9 

seconds:       0    0,1   0,2  0,4   0,8      1      2       3      4

       5 

Ones digit (0 to 9): hold-in power in percent of track 
voltage, 0 - 90%. Applied after the pull-in time elapsed 
(necessary for ROCO coupler, not needed for KROIS 
coupler). 

 

3.16  SUSI-Interface and Logic-Level Output 

All decoders described in this manual (except for the MX681) have outputs that can either be used as 
a SUSI interface, as logic level outputs or for servo control. These outputs are available at solder 
pads or on the decoder plug (MTC or PluX), see the various decoder drawings starting on page 3.  

These outputs are active by default as SUSI interface. They can be switched for the alternative appli-
cations with 

CV #124

 (Bit 7) or 

CV’s #181 and #182

 

(see next chapter “Servo configuration). 

 

CV 

Denomination 

Range 

Default 

Description 

#124 

 

 

Shunting key  

functions:

 

Changing SUSI  

outputs

 

Bits  

0 - 4, 6 

Bits 0 - 4, 6: Shunting key selection and  
                   HALF-SPEED ACTIVATON 

Bit 7 = 0: SUSI active instead of normal functions 
         = 1: Normal function outputs instead of SUSI 

 

Summary of Contents for MX681

Page 1: ...rs 15 3 16 SUSI Interface and Logic Level Output 15 3 17 Servo Configuration 15 4 Feedback Bidirectional communication 16 5 Operating with Märklin MOTOROLA Systems 17 6 ZIMO Decoder Software Update 17 NOTE ZIMO decoders contain an EEPROM which stores software that determines its characteristics and functions The software version can be read out form CV 7 and 65 The current version may not yet be c...

Page 2: ...rations MX681 MX681N MX681R MX681F 7 wires 120mm long for power pick up 4 function outputs Solder pads are available for further outputs MX681 with 6 pin plug as per NEM651 and NMRA RP 9 1 1 mounted to the circuit board Versions with 8 pin plug as per NEM652 on 70mm wires or 6 pin plug on 70mm wires special order only 20 x 11 x 3 5 mm 1 0 A 8 Fu Outputs 2 Servos SUSI MX685 Family Function Decoder ...

Page 3: ...he total current of all outputs Use the soft start op tion i e CV 125 52 to prevent cold start problems of light bulbs in rush current interpreted as a short circuit which leads to the output being turned off Software Update ZIMO decoders can be updated by the user provided that one of the following update devices is at hand ZIMO decoder update module MXULF since 2011 system cab MX31ZL or command ...

Page 4: ...Page 4 Function Decoders MX681 MX685 MX686 MX687 MX688 ...

Page 5: ...Programming in Operational Mode is not locked because any such programming only applies to the active loco address and reprogramming the wrong locomotive is therefore not possible Bit 7 1 Software updates via MXDECUP MX31ZL or other means are locked 112 Special ZIMO configuration bits 0 255 2 Bit 1 0 Normal acknowledgment in Service Mode by activating motor and headlight outputs 1 High frequency p...

Page 6: ...V indicates a possible sub version number of the main version noted in CV 7 The entire SW version number is thus composed of CV 7 and 65 i e 28 15 3 4 The first vehicle address Decoders are usually programmed at delivery to address 3 CV 1 3 for the DCC as well as the MM Märklin Motorola format All aspects of operation are possible with this address but it is recom mended to change to a different a...

Page 7: ... can for ex ample be turned ON OFF with a single loco function key See chapter Function mapping The virtual motor control follows the commands of the second address if one is defined value 0 CV Denomination Range Default Description 64 Short SECOND ADDRESS 1 127 0 The short 1 byte second address it is active when CV 112 Bit 5 0 67 68 Long SECOND ADDRESS 128 10239 0 The long second address it is ac...

Page 8: ...e loco decoder is sufficient CV Denomination Range Default Description 2 Vstart with 3 step curve 1 255 1 Internal speed step 1 255 applied as lowest external speed step speed step 1 applies to 14 28 or 128 speed step modes 1 lowest possible speed 5 Vhigh with 3 step curve 0 255 1 or 255 Internal speed step 1 255 applied as highest external speed step 14 25 or 128 depending on the speed step mode ...

Page 9: ...ymmetrical threshold for stopping with asymmetrical DCC signal Lenz ABC method 1 14 101 114 201 214 0 1 1 4 V 106 Hundreds digit Sensitivity adjustment changes the speed with which the asymmetry is being recognized 0 fast recognition but higher risk of errors i e unreliable stopping 1 normal recognition 0 5 sec pretty save results default 2 slow recognition 1 sec very reliable 29 124 112 Individua...

Page 10: ... with CVs 69 to 82 The commands of the first and the second address are read separately and stored according to the respective function mapping and the desired function output states After power on system boot up longer track power interruption etc the decoder is first waiting for a SECOND ADDRESS command provided the second address is not 0 and the outputs are set based on this secondary address ...

Page 11: ...ves which of course is also useful for locos of other countries The purpose of the Swiss mapping is to switch various states of the locomotive lighting with different function keys i e for situations like driving a single locomotive cars coupled on driver s cab 1 or at the driver s cab 2 push pull shunting etc Using this relatively complex method is of course only expedient if the vehicle is equip...

Page 12: ...ltage sup ply of the decoder see chapter Technical Information Such low voltage outputs are fully stabilized and the voltage will not fluctuate with changes in track voltage Alternatively or in addition to this the dimming effect is not limited to devices connected to full track power but also works with low voltage the PWM pulse width modulation voltage reduction is also available with CV 60 whic...

Page 13: ... function outputs need to be dimmed than CV 60 allows or if some function outputs require a different voltage and the uncoupler function is not needed on the same vehicle then CV 115 can be used for an alternative low voltage supply The respective function outputs must be defined as uncoupler output in the corresponding CVs 125 132 159 and 160 see Special effects for function outputs CV Denominati...

Page 14: ...ulse strobe direction 20 21 22 000110xx Rotary beacon direction 24 25 26 000111xx Gyralite direction 28 29 30 001000xx Ditch light type 1 right direction 32 33 34 001001xx Ditch light type 1 left direction 36 37 38 001010xx Ditch light type 2 right direction 40 41 42 001011xx Ditch light type 2 left direction 44 45 46 001100xx Uncoupler as defined in CV 115 48 49 50 automatic disengagement in CV 1...

Page 15: ...erican railroads The ditch lights will only be working if the applicable bits in CV 33 and 34 are on the definition in CV 125 128 in itself is not enough but a necessary addition Example If ditch lights are defined for F1 and F2 the bits 2 and 3 in CV 33 and 34 have to be set accordingly i e CV 33 13 00001101 CV 34 14 00001110 3 15 Configuration of Electric Uncouplers System KROIS and System ROCO ...

Page 16: ...111 Two key operation F11 F12 112 Two key operation F3 F6 113 Two key operation F4 F7 114 Two key operation F5 F8 Two key mode operates as defined with CV 161 Bit 2 Connecting servos to decoder consult the loco decoder loco manual 4 Feedback Bidirectional communication All ZIMO decoder types have been equipped with a type of feedback ever since DCC was formed which has always been a major differen...

Page 17: ... equipment All ZIMO decoders as of 2009 are able to send their own loco address from an insulated track sections with a so called broadcast method very fast although only for one loco in that section send CV content on demand along with some decoder data such as actual speed in km h load and decoder temperature RailCom in ZIMO Decoders is activated with CV 29 Bit 3 1 AND CV 28 3 These are usually ...

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