Using ESU Logic-level function outputs

[RBrodzinsky]

I have always been intrigued by the logic-level functional outputs on the ESU LokSound and LokPilot decoders. What good are they? How do I use them?  I know can purchase the Streamlined Backshop Aux3/4 board, which provides amplified output for them, but I kept wondering what exactly one could do, and could one use these directly.  Well, this week, the USPS has managed to lose my shipment of boards from Bryan at SBS, so I started digging a bit more.

I found this site, where the outputs are fully explained: http://gibitrains.pagesperso-orange.fr/en/automatisme/logique/logique-02.htm
Basically, as the name suggests, these are simply true logic state outputs from the decoder, without any amplification.  When "on" (function selected), the state of the output is +5V, as compared to the decoders ground; compared with the "amplified" outputs which are really the decoder's "ground" when "on", and the blue wire (common +) is used.

To amplify, one needs either an N-MOS transistor (such as an FDV301N from Digikey), or a bi-polar transistor, which then also needs a resistor on the Aux output. The "gate" or "base" input to the transistor is the Aux output; the "source" or "emitter" input is the decoder ground; and the "drain" or "collector" output goes to the device and then to the decoder's common + (blue wire)

OR, one can use the output directly for low current (<5ma) applications, such as an LED.  To test, I put a warm white 1206 LED, with ~400 ohm resistor in series, between the Aux1 logic output of a LokPilot Direct Micro and the decoder ground.  This would give slightly less than 5ma of current (forward voltage of LED 3.3V). Viola! The LED acted just as if it was on an amplified output!  The only difference was rather than using the blue wire, I attached the Aux output to where the blue wire would go; and the ground wire to where the Aux output normally goes.    (Note: for colored LEDs, which normally have 1.8-2.2 forward volts, the resistor should be upped to about 1000 ohms).

Since, for N-scale, about the only other things one can fit into the locos would be more lights, this saves significant room for not having the deal with an additional board.

[peteski]

What is the main application for those outputs?  I know ZIMO decoders have function outputs that can be configured as logic outputs to for example directly drive RC servo signals.

[RBrodzinsky]

I have never found anything in ESU literature on what the purpose of logic-only outputs were for. My idea will be to use the outputs for lights. Still debating whether I should continue doing amplification, or if just using the logic is safe for the long term.

[jdcolombo]

What is the main application for those outputs?  I know ZIMO decoders have function outputs that can be configured as logic outputs to for example directly drive RC servo signals.

I think it's the same with ESU: the logic outputs were designed to drive RC servos in larger scale engines.  Think automated couplers, for example.  Practical in large scale or O (maybe even in HO these days), but not in N. 

John C.

[Jbub]

I'm assuming these logic outputs are simple on/off functions?  You couldn't use these as a flashing beacon or gryalight with the dimming and flash?

[RBrodzinsky]

I did try using flashing ditch lights, worked perfectly.

But, I have just been pointed to the NEM and NMRA standards, and they call for a maximum supported output on the logic pins of 0.5mA. So, while it works, I guess one shouldn’t rely on this method.

[peteski]

Are these logic outputs explained in any of the actual ESU manuals? If yes, which one?

[wcfn100]

Logical outputs are in the manuals.

Jason

[peteski]

Logical outputs are in the manuals.

Jason

Could you be a bit more vague? 

Are these logic outputs explained in any of the actual ESU manuals? If yes, which one?

I looked over the 88-page one (51972_LokSound_V40_ESUKG_EN_User-Manual_Edition-4_eBook_03.pdf) and the only mention I found was under decoder specifications.  There is a section on "logical outputs" which is unrelated to logic outputs.

[wcfn100]

The LokSound V4 Manual page 22.

6.10.4.1. LokSound with 21MTC Interface
LokSound decoders with 21MTC interface have two additional
outputs besides the 4 standard outputs, namely AUX3 and AUX4.
Since they are pure „logic-outputs“, it is not possible to connect
any external loads directly. External power transistors are required.
Connect AUX3 and AUX4 via the interface; there are no wire
leads. In terms of their functionality, AUX3 and AUX4 are equal to
the other outputs. ESU offers an appropriate adapater board (art.
no. 51968) with transistors

I believe those are the functions being referenced here, yes?

Here's a link to the manual -

http://www.esu.eu/uploads/tx_esudownloads/51972_LokSound_V40_ESUKG_EN_User-Manual_Edition-4_eBook_03.pdf

Jason

[peteski]

Thank you!  So there is nothing special about these function outputs - only the fact that they are not designed to drive any loads directly.  I was curious if they could be configured to be utilized as something other than a function (like drivers for USB or susi bus).  They can't even be used to control servos.  And they are only available on decoders with 21MTC interface connector.

[wcfn100]

They can't even be used to control servos.

They already have 4 outputs for that on the LokSound XL.

Jason

[peteski]

They already have 4 outputs for that on the LokSound XL.

Jason

I realize that, but I was looking at all this from the N scale perspective. Neither if these decoders is suitable for N scale models.  Basically for me this is "nothing to see here, move along  . . ."

[RBrodzinsky]

I realize that, but I was looking at all this from the N scale perspective. Neither if these decoders is suitable for N scale models.  Basically for me this is "nothing to see here, move along  . . ."

The logic Aux3/4 pads can be used in N-scale.  There are pads for them on the Select & V4 Micros (and most of the other decoder versions, too).  See Figure 1 on Page 12 of the LokSound user manual above.

[RBrodzinsky]

Here is an annotated image of the V4/Select Micro's connections

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The whole point of my exercise is I need 6 function outputs for a new install (front/rear headlights; front/rear "tail" lights (red markers, independently operated); flashing front ditch lights.