b_Regal78 Posted January 3, 2011 Share Posted January 3, 2011 For anyone using an iDMX, 512 channels are available for use with DMX devices; however, that does not mean all of the channels can be applied to an intelligent DMX fixture. For example, DMX a hazer or a bubble machine are not considered intelligent DMX devices; they are simply on/off. I could theorically connect 512 bubble machines to one iDMX and make a whole lot of bubbles. DMX wash lighting or moving head devices are considered intelligent DMX devices. They are not just on and off but can have channels at varying levels to create different effect, such as fading from a bright intensity to a dim intensity. To handle both intelligent and non-intelligent devices, the software in the iDMX created 128 intelligent and 512 standard channels (do not add the two numbers together to get a total channel count of the iDMX as the intelligent channels are a "subset" of the standard channels - sort of anyway). I'm not worried about how to assign an intelligent channel vs. a standard channel as I know the iDMX will do this automatically on an as needed basis - the channel is allocated when necessary and then de-allocated. In the bubble machine example, I can have 512 of them because they are on and off; however, my question is how many devices can I have that use intelligent channels? I saw a thread concerning the number of intelligent channels, but it did not cover how they get assigned.Consider this example. I have DMX wash lights, with each light consisting of red, green and blue LEDs. They are considered intelligent DMX fixtures and need to use the iDMX intelligent channels to fade. If I fade the green LEDs on one light only from 100% (DMX stepp255) down to 0% (DMX step 0), I need 1 intelligent channel to handle the fade.Finally, here comes the questions...1) Assume I have the red and green LEDs on at 100% creating the color yellow for one light only. If I fade both colors from 100% to 0% equally, how many intelligent channels do I use in the iDMX?2) Assume I have the red and green LEDs on at 100% creating the color yellow for one light only. If I fade both colors from 100% to 0% at different rates such that the green will take longer to fade than the red, how many intelligent channels do I use in the iDMX?3) Assume I have the red and green LEDs on at 100% creating the color yellow for two lights. If I fade both colors from 100% to 0% equally on both lights, how many intelligent channels do I use in the iDMX?4) Assume I have the red and green LEDs on at 100% creating the color yellow for two lights. If I fade both colors from 100% to 0% at different rates such that the green will take longer to fade than the red and do this on both lights the same way, how many intelligent channels do I use in the iDMX? Link to comment Share on other sites More sharing options...
-klb- Posted January 3, 2011 Share Posted January 3, 2011 As I understand it, zero effort is made to identify multiple channels doing identical things. So it is simply the first 128 channels doing any effects other than on/off.And to be honest, I'm not sure that you come out ahead on memory or CPU cycles if you were to try to identify and process as combined iChans those commands that come in together... Link to comment Share on other sites More sharing options...
Ponddude Posted January 3, 2011 Share Posted January 3, 2011 OK, first off lets start at the beginning. You are a little confused at what an intelligent channel is. An intelligent channel is something that DMX does not support. For example, in LOR we have shimmer, twinkle and the ability to fade shimmer and twinkle. That is not something written into the DMX protocol...it doesn't exist there. On, off and fading are all DMX supported commands written within the DMX protocol. You need a DMX device to interrupt them though. Like a dimmer pack. The dimmer pack just smoothly fades along all 255 steps written into the DMX protocol. This statement is directly from the iDMX manual:"This intelligent device allows access to all 512 channels in a DMX Universe. It also supports 64 intelligent channels that can perform high level LOR controller commands like fades, twinkling and shimmering."So, if you have, lets say a moving head, and lets say it is 5 channels worth, the DMX commands that are sent out are interrupted by that moving head. Channel 1 is usually pan, channel 2 tilt, channel 3 shutter, channel 4 color and channel 5 the gobo. If the controller has a built in dimmer, the controller will also handle the dimming effect without using an intelligent channel.Long story short (I know, too late) when you want to fade a light, it doesn't use an intelligent channel as long as the light has a built in dimmer. However, when you twinkle a light, it is going to use an intelligent channel.There really isn't a way to figure out when an intelligent channel is being used. It is something that the internal software figures out itself. Link to comment Share on other sites More sharing options...
-klb- Posted January 3, 2011 Share Posted January 3, 2011 Greg,Even fading uses iChans. DMX does not support fading. DMX supports consecutive frames, with gradually varying intensity levels, with the net result being a fade. LOR expects intelligence in the controllers, in that it expects to send commands saying start at this intensity, and spend this long going to this intensity. Then LOR won't speak to that channel, until it has something else for it to do..The iChan is necessary to take that command, and convert it to a series of intensities, and insert them into the DMX frames. It doesn't matter if it is a lighting intensity, or a pan position, LOR and DMX don't treat them any differently.Or, to be more clear about DMX, all it really does is repeatedly send the current intensity for all 512 channels. There are no commands, only broadcasts of the current intensities for every channel in the universe. A much different strategy than LOR uses to communicate. Link to comment Share on other sites More sharing options...
Ponddude Posted January 3, 2011 Share Posted January 3, 2011 -klb- wrote:Greg,Even fading uses iChans. DMX does not support fading. DMX supports consecutive frames, with gradually varying intensity levels, with the net result being a fade. LOR expects intelligence in the controllers, in that it expects to send commands saying start at this intensity, and spend this long going to this intensity. Then LOR won't speak to that channel, until it has something else for it to do..The iChan is necessary to take that command, and convert it to a series of intensities, and insert them into the DMX frames. It doesn't matter if it is a lighting intensity, or a pan position, LOR and DMX don't treat them any differently.Or, to be more clear about DMX, all it really does is repeatedly send the current intensity for all 512 channels. There are no commands, only broadcasts of the current intensities for every channel in the universe. A much different strategy than LOR uses to communicate.I am well aware of that which is why I said if the device is a dimmer it will interrupt that as a fade. I said it a few times. Link to comment Share on other sites More sharing options...
Dr. Jones Posted January 3, 2011 Share Posted January 3, 2011 ok I'll handle the easy part...b_Regal78 wrote: Finally, here comes the questions...1) Assume I have the red and green LEDs on at 100% creating the color yellow for one light only. If I fade both colors from 100% to 0% equally, how many intelligent channels do I use in the iDMX? 22) Assume I have the red and green LEDs on at 100% creating the color yellow for one light only. If I fade both colors from 100% to 0% at different rates such that the green will take longer to fade than the red, how many intelligent channels do I use in the iDMX? 1 until the second color fades, then 2 until the first has completed, then 1 3) Assume I have the red and green LEDs on at 100% creating the color yellow for two lights. If I fade both colors from 100% to 0% equally on both lights, how many intelligent channels do I use in the iDMX? 44) Assume I have the red and green LEDs on at 100% creating the color yellow for two lights. If I fade both colors from 100% to 0% at different rates such that the green will take longer to fade than the red and do this on both lights the same way, how many intelligent channels do I use in the iDMX? 4 - see abovealso - I believe the current iDMX supports 128 intelligent channels Link to comment Share on other sites More sharing options...
b_Regal78 Posted January 3, 2011 Author Share Posted January 3, 2011 Here's what I came up with...In studying the actual messaging used by DMX, Dr Jones is, without a doubt, absolutely correct in his answer. Each channel that is being dimmed, shimmering, twinkling, moving, spinning, whatever requires an intelligent channel by the iDMX. A DMX wash light with 3 channels (R,G, needs 3 intelligent channels to fade. Without better understanding the iDMX software itself, I’m assuming that when the DMX light reaches the specified intensity, the intelligent channel is released. As long as the light receives no additional information, it remains in whatever state it is at. To understand the term of intelligent channels as it applies to the iDMX, you need to understand both the DMX and LOR protocols. In LOR (in the simplest form), a single message from the computer is sent to a LOR controller telling a LOR channel to fade up or fade down from some intensity to another intensity in some duration of time. The firmware in the controller itself must then act upon this command adjusting the intensity of that channel over the duration specified. It the fade was to last 10 seconds, that channel would need additional commands from the computer to complete the fade; it would be entirely handled by the controller.DMX protocol is a serial connection. That is, data is being continuously sent to the device. If a run of the mill stage lighting board was connected to a DMX wash light having only a single color (assume it is a 1 channel light with no master dimmer, strobe, and any other extra features), messages are continuous sent with different intensity for that light. To break down this message even further, a break command is sent, followed by a “mark after break” or MAB. This signifies the beginning of a new DMX packet. Following this is the data for each channel in the DMX universe (up to 512 channels) encapsulated by a start bit and stop bits. This constitutes a frame. Up to 512 frames, plus the MAB formulates the DMX message packet.Notice there was no mention of an address (as in a typical LAN UDP packet) in the DMX protocol description. That’s because there is none. In the DMX protocol, there is an implied addressing scheme, or in other words, the frame location is its address. The first data frame in the DMX packet is not used as no DMX device can have an address of 0. The second data frame in the DMX packet is address 1. The third data frame in the DMX packet is address 2. The forth data frame in the DMX packet is address 3 and so on. Given the 1 channel DMX light in the example above, if it had an address of 5, it would use the 6th frame in the DMX message as the intensity value. If the light was fading, the 6th frame would change values in each successive DMX message packet to enable the light to fade. Remember, DMX is serial.Understanding the two different protocols, you should be able to see the need for an intelligent channel the LOR world. LOR sends out a single command that must be acted upon by the controller firmware, on in this case the iDMX. The iDMX must “remember” the duration and intensity start and stop values intensity values to enact the fade on the DMX device (e.g. it must continue sending commands to the device for the fade to take place. The “remembering” is the intelligent channel. In a simple programmatic sense, it would be easy to allocate a “record” (e.g. intelligent channel) that consisted of an address, start time, end time, effect, beginning intensity, and ending intensity (similar to what is seen in a typical LMS file) to produce the fade. Each record would be similar in format. Right now, the iDMX is capable of having 128 records. When the fade is complete, the record is released for reuse by another command. It would be hard from a programming aspect to have a record associated with an unknown number of channels and keeping each record from not duplicating addresses in another record. I don’t know why they could not have 512 records in an iDMX; maybe there is some hardware limitation in the chip.For what it’s worth, I am speculating the way the iDMX works from a programmatic standpoint. The data stream described for DMX is accurate. From what I can see, it is very easy to understand why there is one intelligent channel per channel on a DMX fixture, when the fixture is being enacted upon. The intelligent channels have nothing to do with the number of devices, just in the way the channel is being used for a particular device. If it is an on / off command, no intelligent channels is required. If the command is to be executed over a period of time, such as in a fade or movement, an intelligent channel is required for the duration of that event. Then it is released. Link to comment Share on other sites More sharing options...
b_Regal78 Posted January 4, 2011 Author Share Posted January 4, 2011 Fading is not supported by DMX. On and off only. That is, if it is on, it is at some given intensity. If it is off, the intensity is at 0. In essence, it only supports an intensity level at any given point in time, until the next DMX message is received. A fade is a series of DMX messages changing the intensity a little at a time. Link to comment Share on other sites More sharing options...
Dr. Jones Posted January 4, 2011 Share Posted January 4, 2011 DMX512A and LOR both run on the same protocol -RS485. This is a serial protocol. For every command mark on a sequence a command is sent out through the lor network.I haven't looked at the LOR wave form recently on a scope(2008 when i had issues), but as I recall it appeared very similar to DMX-RDM, in which a bit is sent denoting which controller needs to listen to the following command.LOR Bob and Dan would probably be the best persons to describe what is going on in the signal. Link to comment Share on other sites More sharing options...
Dr. Jones Posted January 4, 2011 Share Posted January 4, 2011 double post Link to comment Share on other sites More sharing options...
b_Regal78 Posted January 4, 2011 Author Share Posted January 4, 2011 Protocol might not have been the best choice of words. It's more like the message format and frequency I was refering to... Link to comment Share on other sites More sharing options...
Tim Fischer Posted January 4, 2011 Share Posted January 4, 2011 EIA-485 (RS-485) only specifies electrical characteristics of the driver and the receiver. It does not specify or recommend any communications protocol.Cite: http://en.wikipedia.org/wiki/EIA-485 Link to comment Share on other sites More sharing options...
-klb- Posted January 4, 2011 Share Posted January 4, 2011 Ponddude wrote:Long story short (I know, too late) when you want to fade a light, it doesn't use an intelligent channel as long as the light has a built in dimmer. However, when you twinkle a light, it is going to use an intelligent channel.This is what I was specifically responding to.. Fading the intensity of a dimmer pack absolutely requires an iChan. Link to comment Share on other sites More sharing options...
jeffl Posted October 17, 2011 Share Posted October 17, 2011 Does anyone here have an idea how to see how many channels in a LOR sequence might be fading at any given point. I would like to be able to calculate how many channels I could get away with on an iDMX without running into problems.I know 128 is possible without any problems but I expect based on how my channels are spread by color and different items I could probably hit a much higher number without any problems.Thanks Jeff Link to comment Share on other sites More sharing options...
Dr. Jones Posted October 17, 2011 Share Posted October 17, 2011 The iDMX supports 128 ichannels - only 128 can be fading at one time Link to comment Share on other sites More sharing options...
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