Odyssey and Electric Railroad Speed Control Question

Not likely.

If the locomotives have the same gearing (motor, worm, trucks, etc.) then putting ERR into both may yield acceptable MU (lash-up) performance. However, from my experience, TMCC MUs work best in absolute speed mode. This means using a Legacy Cab-2 in TMCC mode or the MTH app controlling a TMCC Base-1 and using 32 speed step mode.

Mixing Odyssey and ERR is typically not a great idea.

Thank you all for the responses.  Sounds like the best path forward is to upgrade them both to ERR.

@rplst8 posted:

If the locomotives have the same gearing (motor, worm, trucks, etc.) then putting ERR into both may yield acceptable MU (lash-up) performance.

Hopefully someone else can speak to the gear ratio; if both engines are the same or different.

@Lionel16 posted:

Hopefully someone else can speak to the gear ratio; if both engines are the same or different.

As a general rule, you get a whole lot more specific technical answer when you list the product numbers of the locos in your technical question- VS us speaking in broad generalities.

As a just a search for C-420 https://www.lionelsupport.com/...1&keywords=c-420

There are 6-18xxxx, 6-28xxx, 6-34xxx, 19xxxx, and maybe some even I missed.

The C420's "probably" have the same trucks.  In looking the trucks have different part numbers, but the big clue is that they both use the same drive gear from the worm, which suggests pretty strongly that the gear ratios would be identical.

@rplst8 posted:

Not likely.

If the locomotives have the same gearing (motor, worm, trucks, etc.) then putting ERR into both may yield acceptable MU (lash-up) performance. However, from my experience, TMCC MUs work best in absolute speed mode. This means using a Legacy Cab-2 in TMCC mode or the MTH app controlling a TMCC Base-1 and using 32 speed step mode.

Mixing Odyssey and ERR is typically not a great idea.

In other words (if I understand this correctly), run the Odyssey 1 engine (assuming a later version with an on/off switch) with the Odyssey turned off in order to run it with a TMCC engine that doesn't have Odyssey. Is that right?

Correct, if both engines have similar or the same gear ratios and neither has cruise enabled, they should be able to run together.

@breezinup posted:

In other words (if I understand this correctly), run the Odyssey 1 engine (assuming a later version with an on/off switch) with the Odyssey turned off in order to run it with a TMCC engine that doesn't have Odyssey. Is that right?

They might work, they might not, regardless of the gear ratio. Theres no way to know if the boards have the same motor control profile, or even if the motors are the same.

Model numbers would help narrow it down so we could cross reference the parts.

It can’t hurt to try, but in my experience I usually end up with one engine dragging the other around, or the two fighting each other as one gets traction and the other loses it.

I have the best results with either Legacy control of speed matched locomotives (not all are) or TMCC 32 step absolute step mode.

Conventional also works pretty well, assuming the locomotives are speed matched (same, or very similar drive train, with similar generation of electronics.

Control of MUs via the Cab-1 and Cab-1L never work that well. The Cab-1L is a bit better, but not by much. The problem is that if one of the locomotives misses a speed up or down command, it’s nearly impossible to recover without coming to a complete stop. In absolute speed step mode, if one engine misses a step command, adjusting to a lower or higher step usually corrects it.

So the first engine is 6-18589, the other engine is 6-28218. 

@rplst8 posted:

Control of MUs via the Cab-1 and Cab-1L never work that well. The Cab-1L is a bit better, but not by much. The problem is that if one of the locomotives misses a speed up or down command, it’s nearly impossible to recover without coming to a complete stop. In absolute speed step mode, if one engine misses a step command, adjusting to a lower or higher step usually corrects it.

Never say never.   Here's three TMCC locomotives with cruise running with the CAB1L.  The key to minimizing the issue of missing a relative step is slow throttle movements.

Wow, I never realized running consists in relative speed mode with a Cab1 could create issues, with engines missing speed steps.   I do plan on using a Cab-2 to create the consist.  I will turn off odyssey in the one C420, then try creating a lashup with the Cab-2 in 32-Speed step mode.

Curious, how does relative speed mode work?  Are there an infinite amount of speed steps?

Gunrunner John, thank you for answering the question I had on gearing.

@Lionel16 posted:

Curious, how does relative speed mode work?  Are there an infinite amount of speed steps?

Guess what? 3D printing has a similar concept but with distance coordinates.

Absolute- when you send an absolute format speed step, it's that number. Example speed step 5 is just that, the 5th speed step. This matters because let's say there is a glitch in communications. You are speeding up going 4,5,6,7,8, but the engine didn't "hear" 6. So it continues going 5, and then jumps to 7 when it hears it. Point being, if the engine gets the command, there is no mixup- 5 is 5, 30 is 30.

Relative. Each step is relative compared to the current state- which we assume was the last command received. In other words, each step is plus one, or minus one- compared to the previous state. There is still a limit eventually in the state table of the controller at the engine, but again, command wise, you are sending steps that only represent plus or minus one state from the current state. So in bad communications, you just keep sending more relative speed step changes until the engine receives it and moves faster or slower than before. Again, there are NOT infinite steps, but you can send steps indefinitely until you reach the limit- beyond that they are ignored.

Again:

Relative= sending +1, +1,-1,-1

Absolute= sending 5,7,20,3,4

If one engine receives a single command, but the second engine misses, and then you send another command:

Relative- the engine that missed a command is off by 1 on the first error and remains that way only getting worse and worse out of sync with each missed up or down step. Only a total reset from 0 and then hoping both don't miss any steps or commands.

Absolute- yes, they are out of sync on the missed command, but the next command being absolute- fixes the situation and both are exactly on the same command step.

@Lionel16 posted:

Wow, I never realized running consists in relative speed mode with a Cab1 could create issues, with engines missing speed steps.

Obviously it depends on each railroad, track cleanliness, antennas, signal level, etc. In my case I had very unpredictable results. It may have something to do with the fact that my basement is framed with metal studs. Who knows?

I do plan on using a Cab-2 to create the consist.  I will turn off odyssey in the one C420, then try creating a lashup with the Cab-2 in 32-Speed step mode.

Curious, how does relative speed mode work?  Are there an infinite amount of speed steps?

Vernon answered pretty thoroughly, but as to the number of speed steps in relative mode…

In Cab-1 mode on the Cab-2 or when using an actual Cab-1, the remote will keep sending speed +1 or -1 commands for as long as you spin the big red knob.

Locomotives however will only respond to 32 or 100 of those depending on which version of the electronics are inside. I think some of the TAS boards actually support 128 speed steps. Most ERR boards are configurable between 32 and 100 speed step mode. So once the locomotive gets to 32, or 100, or 128, it will no longer respond to throttle increase commands. Once they get to zero, they no longer respond to throttle decrease commands. In both cases though you can spin the knob as much as you want, lol.

In case the "how to" isn't clear for the CAB2, TMCC is 32 absolute speed steps, and CAB1 is relative speed step mode.  R100 is also relative speed step mode, but it added some embellishment of the displays to allow you to have the speed graph and the  keypad icons.  R100 was specifically added to support ERR Cruise products.

All,

Thank you for answering my questions.  My plan is to try lashing-up both engines using TMCC mode in the Cab2.  If I don't receive favorable results, then I will most likely upgrade both engines to the Electric RR Cruise Commander platform.

Before you lash them up try running them uncoupled and separated a few inches and see how well they are speed matched