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DMX512 DC Pump- network and wiring help needed


TonyB

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Hello, I could use some technical help. I am planning a small scale musical fountain for my backyard. I am currently deciding which design pump to use. My preference is to use a mag drive seal-less DC pump. I’ve come across a manufacturer BLDC Pumps who offers this type of pump in various capacities and discharge head. They also offer styles of “controls” for the pump, 1. Standard 2 wire  DC (hot and ground), 2. A PWM pump which has hot, ground and a PWM wire and 3. a DMX 512 model which has hot, ground and 3 wires for DMX.  I am not familiar with DMX other than what I read in last couple of days. The DMX pump appears to be a good option.  I am planning to control the fountain pumps, servos and lights with Light O Rama hardware and software. In looking at typical DMX lights, there is a DMX in and a DMX out on every light fixture. This is used to daisy chain the lights together.  How could I do this with these pumps?

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This LOR guide gives you a good overview on using dmx and how to get there.

https://store.lightorama.com/pages/light-o-rama-and-dmx

The pump will have several channels assigned to functions such as on and off, speed etc. You will send dmx values from 0 to 255 from the Sequencer which will tell the pump to run at, for example 100 percent speed or dmx 255 on the speed channel.

Start with the above document and come back with ant questions.

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Phil talked about the software side of it, and here is more of the wiring side - which is what I think  you were asking.  DMX uses the RS-485 electrical standard.  In an ideal world, there is a single data network wire that goes from device to device with no splits or Ys in the network.  Each device on the network has a communications chip that ties to that network.  Now that actually means that there is a Y (or tap if you prefer to call it that) inside the box (could be well under an inch of PC board trace).  That is such a small violation of the standard that it does not matter - and is of course expected.  So the question is how much of a Y the standard can handle.  The answer is "some".  So especially if there is a fairly small number of devices on the network, a few feet of wire on the tap should not be a major problem.  So what you would end up with is the data + wire from the pump connected to one of the DMX network wires, and the darta - wire connected to the other DMX network wire.  The DMX network (depending a little on how you generate it, likely will have a + and a -.  And in most cases, there will be a data ground which would connect to the black ground wire.  Therefore, at each pump as far as the network is concerned you would have a tap with the data +, data -, and data ground tapped into your network.  Keep the tap length as short as practical.

Did that all make sense?

 

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Hello Thanks Phil, good read.

 

My specific question as Jim suspected was: How do you connect one DMX fixture to the next one and down the line if the devices have 3 bare wires?
 

The pumps have 1 meter of wires. The wire colors are: 

Blue : pump power (-)

Brown: pump power (+)

Red : DMX data (+)

Black: Ground

Yellow: DMX data (-)

The pumps will be close enough together such that I could pull all of these wires into a junction box. I am planning to create the DMX network using a Cat 5 cable connected to LOR USB to RS485 adapter. 
 

So, do I simply connect all of the same wires together at this junction box and then connect Cat 5 wires :

white  orange to Red pump wires,

Orange wire to pump yellow wire and

white brown to pump black?

do I need a termination resistor?
 

thanks for the help!
 

 

 

 

 

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Last RS485 device on the network should be terminated in 120ohms. That is LOR or DMX or any other use. Some are fussy, some may let you slide.

IMHO Terminate. low power (sub 1W) are cheap

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3 hours ago, TonyB said:

That is just a clean, off the shelf way of doing the NETWORK. You still need power connections for the pumps.

If you are putting all the connections in a single box (because the pumps are very close), Any solid (no poor connections wanted, 3x that when doing power) terminal system  will work. Standard RJ45   (💡 LOR W/P pigtails are perfect. LOR uses those on 50W floods. I use them on ALL my controller boxes) for the network in (and Out. Do include the out... plans change. 😁)

K6ccc mentioned that, as long as you don't add wire length to the pumps, that short length is not counted as a 'Y' or 'T'. (I would not expect the pumps to share a netwotk with props that have many nodes the need the controllers to run at >=500K. Plan on a slower network for the simple (light activity) stuff like these pumps

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Thanks Duck!  Good idea on using the LOR waterproof RJ45 connectors for in and out of the box.  Can you give me some guidance on how to make a solid DMX wiring connections.

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I learned to us ferrules on stranded wires, here on these forums

https://www.amazon.com/gp/product/B00H950AK4/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Is the crimper, I started with a  ferrule assortment, but I mostly use the smaller sizes (EXCEPT for the 12V power leads). A kit is a great starter, then I buy the size I run out of.

Dumb nodes, you use in 4's, Smart in 3's  Your DMX is 3's + power (may be a different gauge)

For Terminal blocks : (your use is a bit trickier)  I use these for power https://www.amazon.com/gp/product/B07FVR17ZP/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

(my PSU have 3 sets of flying leads)  and I use a slightly smaller where I join a few terms together into groups.  You can cut between lugs https://www.amazon.com/gp/product/B08V4W637Q/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

I use them anyplace I want to be able to break apart without cutting (See the one at the bottom, near the hinge. Note ferrules   on almost all wires attached by screws)

https://drive.google.com/file/d/1XssqectruJzV7RgB6YgUAjyPWDy9K_IY/view?usp=drive_link

 

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I ordered the crimper and ferrule assortment kit.

 

For  connecting the like colored DMX wires from each pump together and to the network, I am considering this:

https://www.czh-labs.com/products/oono-din-rail-mount-30a-300v-8x3-position-pluggable-terminal-block-distribution-module

 

For the power wires for the pumps, I’m considering this:

https://www.czh-labs.com/products/din-rail-mount-dc-5-32v-8-channel-pluggable-top-wiring-terminal-block-power-distribution-fuse-module-hcdc-hd064vt
 

I would appreciate your thoughts on this as well as alternatives.

 

 Thank you 

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1 hour ago, TonyB said:

I ordered the crimper and ferrule assortment kit.

 

For  connecting the like colored DMX wires from each pump together and to the network, I am considering this:

https://www.czh-labs.com/products/oono-din-rail-mount-30a-300v-8x3-position-pluggable-terminal-block-distribution-module

Your DMX leads are probably under 20Ga. This might cause grip issues . I guess for the price, it wont hurt to try (besides ferrules will help )

1 hour ago, TonyB said:

For the power wires for the pumps, I’m considering this:

https://www.czh-labs.com/products/din-rail-mount-dc-5-32v-8-channel-pluggable-top-wiring-terminal-block-power-distribution-fuse-module-hcdc-hd064vt
Great. Pick a fuse size at about 125% of the pump draw at start (avoids nuisance blows)

 

I would appreciate your thoughts on this as well as alternatives.

 

 Thank you 

 

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