ElmrPhD
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| posted on 27/9/16 at 02:30 PM |
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Omex 710 5v output capacity
Anybody know how many (milli-)Amps I can take off "5V out" (pin 9C) to run my sensors?
Sorry, my supplier kept the box and literature for himself and disappeared...and the Omex website doesn't answer this question.
My Dash2's "5V out" is maxed out at 50 mA. I'm guessing the Omex 710 can do more since it's expected to run a TPS and
MAP. I won't be using the MAP on my car, so I'm hoping there's a fair bit of amperage left over to run: Race-Tech wheel speed
sensor, Honda coolant temp. sender, VDO oil pressure sender, and eventually a oil temp. sender of some make.
All the above will have pull-up resistors connected.
Thanks for any help you can offer.
Steve, in the NLs
F20C powered MNR Vortx
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ElmrPhD
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| posted on 27/9/16 at 02:43 PM |
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Ok, it looks like the wheel speed sensor is supposed to run off 12V. So, that's one less sensor to pull 5V, but I still need to know if
I'm gonna fry the Omex by drawing off too many milliamps of 5V.
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ian locostzx9rc2
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| posted on 27/9/16 at 03:03 PM |
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Ring omex I'm sure there be able to help
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ElmrPhD
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| posted on 27/9/16 at 03:13 PM |
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Been waiting for them to reply to my email. Sometimes they do, sometimes they don't...
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ian locostzx9rc2
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| posted on 27/9/16 at 04:26 PM |
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Phoning them maybe better always very helpful .
[Edited on 27/9/16 by ian locostzx9rc2]
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liam.mccaffrey
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| posted on 27/9/16 at 05:43 PM |
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This is'nt a dig in anyway but I'm always surprised that people expect to get actually get a reply to an email. I've very seldom
had replies to emails in the past whether its councils, complaints, small/big companies etc.
I have though phoned Omex before and they were super helpful. I spoke with a proper tech guy who even phoned me back when he promised.
all the best
Liam Mc
Build Blog
Build Photo Album
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jeffw
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| posted on 27/9/16 at 07:36 PM |
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Why do you think you need to supply 5V ref to all these sensors? These are the ones you are connecting to the 710 and not the Dash2?
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rachaeljf
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| posted on 27/9/16 at 07:57 PM |
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^What he said! The only sensors that need 5V are the ones used directly by the ecu. Gauge senders should be 12V.
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ElmrPhD
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| posted on 27/9/16 at 08:02 PM |
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Sheez guys:
- I'm in Holland, as it shows to the left, so an email is cheaper than a phone call to the UK
- I don't know what I'm doing or much about electrics and have gotten help via LCB in the past
- As I understand it, 5V output from a sophisticated Dash2 or Omex is more stable, etc. than the standard 12V tap.
- If you can't help, then why proceed to bother me?
Does anybody know the output capacity in (milli-)Amps of the Omex 710?
Thanks for any HELP you can offer.
Steve, in the NLs
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jeffw
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| posted on 27/9/16 at 09:20 PM |
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Lets roll this back to the beginning.
What sensors are you actually wanting to connect to the 710 (Coolant, TPS, Wheel Speed (?)) and what are you using on the Dash2 (Oil Temp. Oil
Pressure, Fuel and/or wheel speed?)
The 50mA on the 5V line is enough to run 4 analogue inputs and the wheel speed/rpm feed is separate to this.
I've got a Dash2 with a Omex 600 and use 3 analogue inputs (fuel, oil pressure, oil temp) on the Dash2 plus wheel speed. The Omex has rpm,
coolant temp, ambient temp and MAP. I have the Omex to Dash2 serial cable to look at all the data from the ECU.
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Rich J
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| posted on 28/9/16 at 07:21 AM |
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I've just fitted one of DC/DC Converter Regulator 12V Stepdown to 5V 3A 15W Car Power Supply Module UK based on the
advice of Race Technology as I was getting close to "overloading" my Dash 2
Works a treat 
[Edited on 28/9/16 by Rich J]
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ElmrPhD
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| posted on 28/9/16 at 08:53 AM |
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Wow - THANKS JEFFW!
That was truly helpful. I beg you to continue!
But before I waste any more of your valuable time, let me first ask if:
For the current draw calculations, does one add the pull-up R's value to the resistance of the sender to get I=5V/(pull-up R + sender R)? If
so, then the current draw is 30 mA each for my VDO senders (Fuel, Oil P.) and merely 1.1 mA for the Honda coolant sensor. (I haven't yet bought
and don't know which oil temp sensor I will use.)
In this case, it would appear that my 5V line current demand is not as bad as I first calculated. So, I can probably proceed without your help...for
now. If not, then, please read on to see my more elaborate reply to your questions.
Again, please note that I received no documentation/literature/instructions with my Omex, so everything I know is off the internet, which provides a
lot, but not enough for my apparently poor understanding of electrics.
For the 710, I need to connect, as you say, "Coolant, TPS..." but not Wheel Speed. I plan to connect Wheel Speed only to the Dash2 and it
needs 12V, not 5V, so not part of my problem.
For the Dash2, I also need to see coolant temp, so I plan to share the signal between 710 and the Dash2. I know the preferred method is to have a
separate coolant sensor, but the Race-Tech' tech told me that the signal can PROBABLY be shared. I'm not so sure, but really want to
avoid trying to install a second sensor, if possible.
For the the Dash2, I also need the 4 parameters that you mention: "Oil Temp., Oil Pressure, Fuel (and Wheel Speed, which again, won't
require 5V)"
Thus, 5V requirements for the Dash2 are Coolant, Oil Temp, Oil Pressure and Fuel. Then the TPS to the 710 adds another 5V demand. Again, I'm
not using a MAP sensor.
My dilemma is with your statement that, "The 50mA on the 5V line is enough to run 4 analogue inputs ..."
Race-Tech' stress that 50mA is all that the Dash2's 5V line can manage. The fine print further states that a (low R sensor with
associated low R pull-up R) VDO sensor like I have, will draw/consume most of that. For that reason, I am asking if the Omex 710 can provide all the
extra amperage needed to drive the other sensors.
The Race-Tech' tech sent me 1500 Ohm resistors (for the Honda coolant sensor) and 150 Ohm resistors (for VDO fuel sender, VDO oil pressure
senders).
Ok, as I've just realized that I might be ok (and hence inserted the "Before I waste your time..." statement above, I'll stop
and see how you respond.
Thanks again for your valuable help.
Steve, in the NLs
quote:
Originally posted by jeffw
Lets roll this back to the beginning.
What sensors are you actually wanting to connect to the 710 (Coolant, TPS, Wheel Speed (?)) and what are you using on the Dash2 (Oil Temp. Oil
Pressure, Fuel and/or wheel speed?)
The 50mA on the 5V line is enough to run 4 analogue inputs and the wheel speed/rpm feed is separate to this.
I've got a Dash2 with a Omex 600 and use 3 analogue inputs (fuel, oil pressure, oil temp) on the Dash2 plus wheel speed. The Omex has rpm,
coolant temp, ambient temp and MAP. I have the Omex to Dash2 serial cable to look at all the data from the ECU.
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jeffw
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| posted on 28/9/16 at 10:45 AM |
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You would alleviate some of your issues by connecting the Omex 710 to the Dash2 using the ECU serial lead they sell.
If you do that you'll only need Oil Temp/Pressure & Fuel on the analogue ports which will work in the 50mA limited. You will also be able
to display on the Dash 2 anything the Omex sees (throttle angle, injector pulse, etc etc.) If you then use a DL1. Dash2pro or Video4 you'll be
able to log this data.
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ElmrPhD
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| posted on 28/9/16 at 11:48 AM |
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Really? Only 1 GBP and my problems are solved??? What a wonderful solution!!
Thank you!!!
quote:
Originally posted by Rich J
I've just fitted one of DC/DC Converter Regulator 12V Stepdown to 5V 3A 15W Car Power Supply Module UK based on the
advice of Race Technology as I was getting close to "overloading" my Dash 2
Works a treat
[Edited on 28/9/16 by Rich J]
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rachaeljf
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| posted on 28/9/16 at 12:02 PM |
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Sheez
Sorry to have bothered you Elmer. At least you are now being steered away from mixing "referenced" 5V supplies from two separate devices.
The Dash2 quotes its analogue inputs as "0-12V" so you don't *need* to use the Dash2's 5V reference; use a 3 pin 12V regulator
to supply your dash and senders with suitable pull up resistors and you will have quite sufficiently accurate gauges to gaze at.
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ElmrPhD
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| posted on 28/9/16 at 12:25 PM |
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No, YOU didn't bother me at all and I very much appreciate the advise. I just don't like being told by a couple OTHERS that I made a
mistake by emailing instead of calling. I have my reasons...
The "0-12V" thing had me worried as a car's voltage can go well beyond 12V when under way. Never thought about a 12V regulator like
you mention - not sure I even knew such a thing existed. So, again, THANKS!.
So, you're saying that I cannot use the 5V out line from the Dash2 to supply some sensors and the 5V out line from the Omex to supply others if
all the sensors are to be displayed on the Dash2? Damn. Thought I finally had it figured out.
What about the wonderfully cheap 5V 3Amp device that "Rich J" suggested:
DC/DC Converter Regulator 12V Stepdown to 5V 3A 15W Car Power Supply Module UK
to supply all of them?
Thanks, again,
Steve, in the NLs
quote:
Originally posted by rachaeljf
Sorry to have bothered you Elmer. At least you are now being steered away from mixing "referenced" 5V supplies from two separate devices.
The Dash2 quotes its analogue inputs as "0-12V" so you don't *need* to use the Dash2's 5V reference; use a 3 pin 12V regulator
to supply your dash and senders with suitable pull up resistors and you will have quite sufficiently accurate gauges to gaze at.
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rachaeljf
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| posted on 28/9/16 at 10:28 PM |
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Fair enough!
It's probably not so important for gauges but it's not good practice if you mix "referenced" 5V supplies from two separate
devices. The two "5V" can drift relative to each other. This is because each device uses its own ground potential to reference its own 5V.
It's likely the two devices will be grounded to different parts of the car and the two ground potentials will drift relative to each other as
current swirls around the car.
The ecu grounds are recommended to be taken back to the engine block because the sensors the ecu uses are usually single wire items grounded to the
block. This ensures any voltage drift is minimised and the sensor readings the ecu gets are reliable.
If I were concerned about overvoltage and wanted super accurate gauges, I would use a 12V regulated supply for the Dash2 and its senders. Let the Omex
ecu and Dash2 communicate via the serial lead as recommended above.
The 12V -> 5V regulator used by Rich J is fine too (the Dash2 still needs a 12V supply though!), just make sure you ground it and the Dash2 to the
same ground point on the car and you don't need to use the Dash2's own 5V output.
Hope that helps!
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jeffw
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| posted on 29/9/16 at 05:23 AM |
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https://www.race-technology.com/wiki/index.php/ECUType/OMEX600And710
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ElmrPhD
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| posted on 29/9/16 at 11:57 AM |
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Hey, this is great! Thanks soooo much for the explanationS. I'm learning alot - which needed to happen!
I will order the super-cheap 12V-->5V regulator and run all sensors off of that.
Question: Any reason not to also drive the Honda TPS from this 5V regulator?
Thanks again, to you, Rich J and JeffW for your generous help.
Steve, in the NLs
quote:
Originally posted by rachaeljf
Fair enough!
It's probably not so important for gauges but it's not good practice if you mix "referenced" 5V supplies from two separate
devices. The two "5V" can drift relative to each other. This is because each device uses its own ground potential to reference its own 5V.
It's likely the two devices will be grounded to different parts of the car and the two ground potentials will drift relative to each other as
current swirls around the car.
The ecu grounds are recommended to be taken back to the engine block because the sensors the ecu uses are usually single wire items grounded to the
block. This ensures any voltage drift is minimised and the sensor readings the ecu gets are reliable.
If I were concerned about overvoltage and wanted super accurate gauges, I would use a 12V regulated supply for the Dash2 and its senders. Let the Omex
ecu and Dash2 communicate via the serial lead as recommended above.
The 12V -> 5V regulator used by Rich J is fine too (the Dash2 still needs a 12V supply though!), just make sure you ground it and the Dash2 to the
same ground point on the car and you don't need to use the Dash2's own 5V output.
Hope that helps!
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jeffw
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| posted on 29/9/16 at 12:16 PM |
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Run the TPS from the ECU or you will have some potentially serious issues.
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ElmrPhD
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| posted on 29/9/16 at 05:29 PM |
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Hi jeffw,
Thanks for that, but you know I must then ask: Does that not violate the "Thou Shalt Not Mix 5V Referenced Supplies" requirement?
Thanks, again,
Steve, in the NLs
quote:
Originally posted by jeffw
Run the TPS from the ECU or you will have some potentially serious issues.
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jeffw
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| posted on 29/9/16 at 06:59 PM |
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Not really. TPS is essential for the ECU and all three wires have an attachment on the ECU (Orange, grey and pink according to the wiring diagram).
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