I have read extensively about this issue but I had a problem with it this evening. I thought for the last three months I had been doing everything right according to the DT402 manual but evidently not.
I am running a DT402 through a Zephyr extra. I know that the Extra only has 20 slots but I thought I had been releasing the address from both the throttle and system following the directions. But this evening as I was trying to run a new locomotive I got the slotmax problem. I reset the Zephyr to purge the addresses. But when I plugged the DT402 back in it still would not let me enter a new address. I did discover if I hit loco, disp, I could enter the new address. But am I just putting addresses back into the slots on the Zephyr?
I am confused? The instructions in the manual are not real clearcut about the exact steps to release the address from the system’s slots. Here they are-
Use the throttle to make the locomotive’s speed zero (this step is optional but strongly recommended as the loco will continue to move if speed is not reduced to zero).
While the loco’s address and speed information is displayed, press the lOCO key to go into select mode. This will release the address from your throttle immediately.
The address will begin to blink in the display. Press the DISP
You have used up all 22 ‘slots’ on your Zephyr Xtra. The problem is that you have not ‘dispatched’ locomotives as you have used them - Your need to select the locomotive number(if not already in the display) and then press DISP to clear the number from the stack. EXIT needs to follow the DISP command(to get you out of the dispatching …).
The key is making sure the speed is 0 AND all functions are turned off - otherwise the loco will not be released.
Not sure which option you used to clear the slots, but the Zephyr Xtra does not have OpSw 36 to clear the slots, you need to use OpSw 39 which is a full system reset. Or just select an existing loco and then make sure the speed is 0 and all functions are off, then do the Loco, Exit. repeat for the various addresses you used.
I use option switch 39 once a month at my club on both of our layouts. Some of the members never get the idea of properly dispatching and nothing I say to them means anything. I also use this step to seperate locos that have been MU’ed without having to do it manually. Our empire builder has been full several times with the 22 slots, but our super chief has never been full with its 1,200 slots.
With Digitrax, if you leave the throttle set at more than 00%, if you leave any functions on, and if the address is MU’d to any other number or is the top engine in an MU, it will still count against the Slot=Max.
Also am I right to assume the dt402 only displays what is on the command station? I still cannot seem to get the DT402 to release an address I have just run. When I press loco, the address i am running and have stopped with all functions off, then DISP and go back to press loco the previous address will blink as if its still in the system and wants me to select it. Should I be pressing exit instead of DISP.
On your DT402 display, you will see the address of the engine you are running. I have engine ‘1234’ running right now. If that is the engine you want to remove, do the following:
Make sure the throttle speed is ‘00’
Turn off the headlight(F0) and any other function you have turned on.
Press ‘LOCO’(If you want to dispatch a different number, type it in after pressing ‘LOCO’)
Press ‘DISP’
Press ‘EXIT’
The throttle on that side should go to SEL(flashing).
I just did the following with a DT402D plugged into a DCS51(Zephyr Xtra). The address 1234 will be free, but stays in the memory until a new request bumps it out. This should be transparent to the user. If you have JMRI Decoder Pro, you can look at the LocoNet ‘Slots’ and see what is happening(and how many slots are tied up).
BTW, the Digitrax DCS100/200 Command Stations support 120 active engines(not 1200). Our club has gotten into the ‘slot max’ issues several times due to folks not breaking down consists and dispatching off. We have a policy of either reseting the Comand Station(opt 36) or use Decoder Pro to ‘Free’ the slots as needed.
When you dispatch locos you turn off all functions and set speed to 0. You then press loco then dispatch. When you repress loco to aquire another address the previous address pops up. Just enter the new address over the old one and press loco.
This is the info I needed. I see now my DT402 is working normally.
Thanks you guys saved me from going back to NCE. Which is a very good system I just like some of the things that Digitrax does for me better. I still use a Powercab at the bench for programming new locos.
I do need to go the JMRI route but thats a question for another day.
It would be nice to have that many slots but it just wouldn;t work. The packet delay trying to send commands to that many locos with the current NMRA DCC standards would result in such lag, everyone would think their trains were out of control. Even a more modest 500 is really too many, if you calculate the packet time using the average DCC packet size. Best you could do it get 1 packet in every 500 to your specific loco.
I use an original Zephyr and a DT300 and a UT4D, and unless this combination works different(it’s not supposed to), then you DO NOT have to make sure all the functions are off to release a locomotive, you just have to make sure the speed is set to zero.
People often make a bigger deal about releasing a loco than is necessary. All you have to do is make sure that the speed is set to zero on your current loco when you go to select another one, if it is, then it will automatically be released - there is no need to go through a separate step to release the loco. If you left the loco running intentionally, and later need to release it, just select it, stop it, and select another one. Again, this works with the Zephyr, DT300, and UT4D - it is supposed to work the same way with the DT402, but I guess it could be diffferent.
I think the biggest cause of the “Slot Full” message is people accidentally selecting the wrong loco. They select a loco and turn up the throttle but it doesn’t move. They then realize they entered the wrong number so they go to select the correct one without first turning the throttle back to zero.(I know I’m guilty of this myself sometimes)
Our club’s DSC200 command station will hold the slot if the headlight is ‘on’. I have tested this and even spoke with a Digitrax tech about this issue. When a locomotive is ‘Dispatched’, the memory slot is not cleared. It will be purged if it is the next slot available and a new locomotive is added. Auto Purging will set the slot available after the time-out value expires. But if it is not the next available slot, it will not be deleted from memory. You can view this with JMRI under the LocoNet Slots feature.
Now there is a CV in the Command Station to set the ‘auto purge’ timeout’ and another to disable the auto purge - But they arte not the default. I suspect our ‘old’ DCS200’s and my really old DCS100’ may have an older firmware version(My DCS100 is not upgradable to the expended functions). My DCS51 in the ‘Man Cave’ seems to auto purge fine, but I am very careful to break consists/dispatch when testing now installs.
I was running one of my engines a couple of weeks ago at the club, and ‘dispatched’ before I left. When I came back a week later, the engine was still in the ‘slots’, and it had the headlight function ‘on’ and the throttle was a ‘3’ - We all get caught at times!
As I mentioned before, we purge the slots every month(or even sooner) as normal maintenance. And I make sure we purge before any big show - And then we test several ‘trains’ that will be used for running.
My clubs former President (no longer a member) used to just pick up his locos while they were running and never dispatch them. When he ran the same loco at another meeting it would take off at the speed it was previously running at and smash into whatever was in its way. Which is why I do the reset of the DB150 qne the DCS200 once a month.
I too have an original Zephyr, and the only time I EVER got a FULL message on the console or a Slot=Max on my DT400 was when I deliberately added addresses to validate if the system could store 10 or 12 addresses. It’s documented as 10, but there really are 2 more slots it can use (from the Jump Ports) for a total of 12 - when I tried to enter a 13th unique address, I then got a Slot=Max. That’s the only time in over 10 years of having it that I ever got the message. And I have a lot more than 12 locos with decoders and unique addresses.
I have seen it at the club, when there are a dozen people operating, and most of them with UT4 throttles. Also a lot of Steal messages, ebcause people aren;t dispatching properly, partly because of the potentiometer knob on the UT4. Is it REALLY at speed 0? This despite telling people to also flip the direction switch to the center brake position. And set the address knobs to all 0 when they are done using the throttle.
You bring up a point that I’ve asked about in several forums and never received a good answer in return: Given the available bandwidth (specifically based on the standard DCC data rate on the rails) and sufficient amperage, what is a good approximation of the maximum number of locomotives/consists that could be run on a DCC system? And by approximation, I mean either a ballpark number, or a general formula.
Obviously, one would have to make assumptions about how often each train would need to receive a command, based on arbitrarily choosing some typical interval for adjusting speed and turning functions on and off, as well as how often a given command station would be set up to refresh/repeat commands at the railhead.
Obviously in an implementation using Advanced consisting the actual number of locomotives in use wouldn’t be a concern as compared to the number of actual individual trains rolling. For the sake of simplicity, it would make sense to eliminate accessory decoder commands from consideration.
The typical answer I get back is a dismissive “more than you’ll ever want to run”, but that’s not the point of the exercise, really. I figure that someone out there probably has worked this out already.
I’ve actually looked into this some. The nominal duration of a 1 bit is 116 microseconds and the nominal duration of a 0 bit is at least 200 microseconds. The minimum number of bits to send an intruction packet using primary addressing, often called two digit addressing, and 14 speed steps with headlight control or 28 speed steps with no funtion control is 42 bits, including 14 preamble bits and 28 packet bits. The minimum number of 0 bits in such a preabmle/packet combination is 11. Therefore, the minimum time for one instruction packet is 11200 + 31116 = 5889 microseconds, giving a maximum instruction repeat rate of 169 instructions per second.
Again, this is the MAXIMUM rate and the actual rate is going to be less. Just adding function control is going to at least cut this in half, and using extended addressing or 128 speed steps is going to reduce it even further.