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 key to dis- patch the address on the throttle and the address will be released to the sys- tem and marked as a dispatched address. See Dispatching below. Pressing the EXIT key releases the address from both the throttle and the locomo- tive stack in the system. The display on your DT402 will show SEL for the throttle.
If you press the lOCO key again, the throttle will begin flashing the address you just released. You can re-select that address by pressing the lOCO key or you can use the throttle knobs or key pad to browse to a new address and select it instead.
What I am confused about is in number 3? I have been stopping the loco that I am running, hitting the loco key and then the exit key. Does this not release it from the system, or am I supposed to do something with the DISP key first? I can't figure out why I got the Slot=Max message.
Thanks
SB
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 ....).
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
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.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
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.
Is the procedure the same as for 36 but placing 39 in instead?
sb
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.
Paul A. Cutler III
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.
Maybe i left the lights on with those locos still there I will try this in tomorrow.
Thank you for the help,
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.
retsignalmtr 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. I think you mean 120 slots !!! 1200 slots would be a dream for large Digitrax users . ---- Ken
KemacPrr retsignalmtr 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. I think you mean 120 slots !!! 1200 slots would be a dream for large Digitrax users . ---- Ken KemacPrr retsignalmtr 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. I think you mean 120 slots !!! 1200 slots would be a dream for large Digitrax users . ---- Ken
KemacPrr retsignalmtr 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. I think you mean 120 slots !!! 1200 slots would be a dream for large Digitrax users . ---- Ken
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)
Robert,
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.
rrinker 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. --Randy
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.
-Fritz Milhaupt, Publications Editor, Pere Marquette Historical Society, Inc.http://www.pmhistsoc.org
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 11*200 + 31*116 = 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.
There you go. And the average rate will be someone lower than that, since that is the conditions with the absolute minimum packet size.
So you can see, trying to address even 200 locos simultaneously will take more than 1 second for each packet to hit a given loco. Means more than a secod for the shortest possible horn blast, since there is an F2 on and then an F2 off sent when you press and release the horn button. And reality would be worse, since we're now adding function control packets in with the periodid speed refresh packets.
So while the idea of using a PC as the command station instead of some proprietary hardware seems great, it really doesn't buy us anything other than needing to use a far more powerful (and energy using) computer than is really needed to control a reasonable number of locos. The small embedded processor chips used in most brands is more than powerful enough to meet the requirements. To address more simultaneously will require a completely revised protocol, or at least require it to be sped up. The danger of making bit times significantly smaller is that will increase the chances of itnerference. More checksums could be added to the protocol to ensure that the messages are received as intended, but that would eat into the gains realized with shorter bit times by requiring more bits per packet.
CSX Robert 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 11*200 + 31*116 = 5889 microseconds, giving a maximum instruction repeat rate of 169 instructions per second.
That is exactly the kind of analysis I've been looking for-- Thanks!
Having had both a Digitrax Chief and now a NCE system I can say that the NCE system has a much larger active loco capability than Digitrax. When using the Chief I normally ran at 110-115 slots used during an op session. Every so often the slot max message would pop up and I would have to break up a few consists to give me room. When I went to NCE I have had over 225 locos in active service with no problems and no slow down in control. The newer ut42 and dt402 handsets have the capability of more than 120 slots but the big problem is that the handsets older than that do not and would not be able to activate the higher slots. AJ always stresed backwards compatabilty and that is a problem now that limits system capacity.
I was a beta dt 402/UR-92 tester a few years back and talked with them numerous times about the capacity problem. Most customers will not see it only the large clubs and home layouts mainly running diesels which have been consisted. If Digitrax had used advanced consisting as their standard instead of Universal the problem would not have existed until someone built more than 120 consists. Their existing adaptation of advanced consisting is a pain to use. The NCE method is much more user friendly. Both have strong followings and both systems work great within their limitations. -------------------- Ken McCorry
225 locos in service each with a unique address, or 225 running locos with maybe 100 or less actual addresses in use because of consisting? It would be interesting to see what would happen if you actually set 200+ locos running - most of them would have to be free-running (not selected on a cab) because you can only have 63 cabs. Based on the NMRA packet size calculation, there would be well over a second delay sending commands.
The big difference is in considing, a 5 unit consist in NCE will typically use only 2 addresses. The lead, and then each of the additional units will have the same value in CV19. You are generally only sending 1 speed/direction packet to all 5 locos.
If you change nothing, Digitrax defaults to the command station managing the consists. So for a 5 unit consist, there are at least 5 address slots in use, and possibly a 6th as the consist address does not have to be the address of any loco in said consist. If instead you would use CV19 consisting with Digitrax, it would behave the same way, you could have 50 locos running together in some massive power move and there would only be one speed and direction packet sent every cycle, instead of 50. You could run 500 locos with just 10 packets, which would be no delay at all.
If anything, NCE has a lesser processor capability, because the limit is 63 cabs. Digitrax can run 120 cabs. And this is the reason given for NCE shutting off the main track when using the program track - it would slow things down too much. I don't have this issue with my home system, nor does it seem to be an issue on the club layout, to be using the program track at the same time others are running trains. There seems to be no slowdown or delay.
During my early Conrail era I had the largest number of units on the rr ready for service 265. The majority were already
consisted sitting in staging tracks . The most individual units in consists I recorded was 241. Some of my ore trains had 4-6 units per train. Most trains had 2-3 unit as a norm. I have 72 staging tracks on the railroad. Then I have 4 engine terminals again with some consists all made up and single non consisted units. So the active loco slot problem with Digitrax was a problem for me. While the processor capabilities of the NCE system may be less for number of handsets it far exceeds Digitrax in the number of active locomotives it can operate. I run 28 handsets in a normal op session. Of these 26 are radio. Both systems can handle this . I've yet to see a rr with more than 30 handsets in service at once so the 63 handset limit with NCE does not really limit the system in my opinion.
My programming is done on a seperate Power Cab off the rr so shutdowns when programming are not an issue. Again for the vast majority of dcc users either system will do what mosr people require in a timely manner.
------- Ken McCorry
Again, it's masked by the differences in consisting. I can assure you that if the locos were consisted with CV19 on Digitrax, that many would all work just fine in Digitrax. Say 50 consists of 6 locos - using CV19 consisting this is just 50 address slots out of 120. Even if the top address is kept seperate, that's 100 out of 120. For 300 total locos. Enough power and enough layout, you could run 120 consists of 6 locos each, 720 locos. Or maybe 10 locos per consist - 1200 locos.
The default method of consisting with Digitrax, 235 locos would need 235 slots, not going to happen. If there were 100 in consist and 10 others selected, you'd be at 110 slots and it doesn't take many people not releasing their selected address before you hit 120 and slot-max. If those 100 locos were in consists of 5, using CV19, they would only take up 20 addresses, leaving a cushion of 100 before slot=max.
That is true. However when sound enters the arena the method that Digitrax uses for advanced consisting requires additional work with cv 21/22 so that the sound functions will work when using the consist address. NCE has the command station alias the consist address to either the lead or rear unit in a consist versus the Digitrax method which requires the use of the consist address 1-127 to operate the consist. If no computer is used tied into the dcc system to assist ,one must keep a written account of what consist address has been applied to the locomotives. With NCE you simply use the number on the side of the unit. Eventually Digitrax will do an upgrade to their command station which would allow more slot capacity. Their current processor is a 386 based unit. When this happens the older dt-100/200/300 and 400 series handsets will not be able to access the slots over 120. The newer dt-402/ut-42 have this capability. --- Ken
I never could see any reason to do consisting with my engine sets as they usually stay running together for months at a time!
So each engine set has the other engines reprogrammed to the highest engine number in the set!
This eliminates ANY delay in the engine movement when the speed command is given!
With 85 engines on the layout and i need to do a Command Station RESET - it eliminates having to go around and reconsist a bunch of engines!
While some will break down consists on during an OPs Sessions I find no need to do so!
BOB H - Clarion, PA
KemacPrr...I've yet to see a rr with more than 30 handsets in service at once so the 63 handset limit with NCE does not really limit the system in my opinion...
I know there have been NTrak setups with more than 63 operators at once, at the 2008 N Scale Convention they had as many as 93. Also, with NCE input devices for things like occupancy detection and control panel inputs take up cab addresses, but with Digitrax input devices do not reduce the number of allowed cabs.
KemacPrr...Eventually Digitrax will do an upgrade to their command station which would allow more slot capacity. Their current processor is a 386 based unit. When this happens the older dt-100/200/300 and 400 series handsets will not be able to access the slots over 120. The newer dt-402/ut-42 have this capability...
The DT402's do have a "XP Slots" option, so it does look like they intend to expand the slots. I don't know how they plan on doing it but this is what I would like to see them do: They could have a separate table for consists and still use the 120 slot table for active single units and active consist "Top" addresses. You would still need a DT402(or possibly a PC) to build the consists using the expanded slots, but any 4 digit Loconet throttle could select and run any loco or consist. You would still be limited to 120 active single units or consists, but with DCC's bandwidth I don't consider that a problem. You could even still use older 2 digit Digitrax throttles by using Digitrax's dispatch/acquire functions.