Maximum draw on the 12VDC output on the serial RJ12 port?

pete_c

Guru
Playing with my little widget here and thinking of taking the 12 VDC for my stuff from the RJ12 on the OmniPro 2.
 
What is the maximum draw on the 12 VDC output there?
 
Without using the radio on the micro router thinking the draw is only some 100 milliamps or so.
 
Does anybody know?
 
Thank you Mike.  The Power point presentation does provide the technical specs for the OPII panel except for the RJ12 serial ports proving 12VDC.  The voltage must be utilized for some some OmniPro powered controllers.
 
 
 
I am guessing though that I am way less on the draw anyways with the microuter.  I am currently using the regular 12VDC output to a voltage conversion gizmo and want to reduce the footprint a bit and do less wires.
 
pete_c said:
Playing with my little widget here and thinking of taking the 12 VDC for my stuff from the RJ12 on the OmniPro 2.
 
What is the maximum draw on the 12 VDC output there?
 
Without using the radio on the micro router thinking the draw is only some 100 milliamps or so.
 
Does anybody know?
 
Does the RJ12 serial port provide a true 12V power output?  That would appear to be undocumented. Or are you thinking of drawing parasitic power from the signal wires?
 
If you are trying to draw power from the RS-232 signal wires, how much you can draw will depend on the drivers that the OP2 uses on the serial port.  Some drivers are capable of providing as much as 45 mA, but others limit the current to lower values, such as 5 to 10 mA.  Also, as the current increases, the voltage you see at the output will likely decrease.  So the device you are trying to power may not be happy as the voltage drops.  I'd be very surprised if the OP2 can drive 100 mA.   There are some devices that use 5V drivers, rather than 12V.  I wouldn't expect that on the OP2, but something to check for.
 
I would try connecting a few resistors across the outputs and measuring the voltage across the resistor to see what the OP2 is capable of.  Say 1.2K for roughly a 10 mA load and 220 ohms for a 50 mA load.
 
Thank you Ral
 
Does the RJ12 serial port provide a true 12V power output? 
 
I personally have no clue as I am just looking at the diagrams right now.  Baby steps here as I do not want to trash my OmniPro 2.  I am curious as I have never seen any RS-232 standard cabling that provided 12VDC.  That said guessing this pin / 12VDC is some propietary HAI thing?  It has been mentioned here before with some guesses as to its use.  Not sure if anybody here today is using said 12VDC for anything though?
 
RS-232.jpg
 
That would appear to be undocumented. Or are you thinking of drawing parasitic power from the signal wires?
 
I want to power up the GLiNet micro router from the 12VDC pins on the RJ12.  I am doing this right now from the 12VDC aux terminals.
 
If you are trying to draw power from the RS-232 signal wires, how much you can draw will depend on the drivers that the OP2 uses on the serial port.  Some drivers are capable of providing as much as 45 mA, but others limit the current to lower values, such as 5 to 10 mA.  Also, as the current increases, the voltage you see at the output will likely decrease.  So the device you are trying to power may not be happy as the voltage drops.  I'd be very surprised if the OP2 can drive 100 mA.   There are some devices that use 5V drivers, rather than 12V.  I wouldn't expect that on the OP2, but something to check for.
 
I would try connecting a few resistors across the outputs and measuring the voltage across the resistor to see what the OP2 is capable of.  Say 1.2K for roughly a 10 mA load and 220 ohms for a 50 mA load.
 
Thank you Ral. 
 
This is where I am venturing to the unknown.  I was going to make up another RJ12 cable only connecting the 12VDC / ground pins to see what happens.  I am thinking that maybe the 12VDC is always present on said pins?  This is not a standard signal wire and appears to be some propietary thing with HAI.
 
Pins 2,3,4 & 5 work fine for me right now and never really thought of using 12VDC to drive the power for the microrouter.  Trying to lessen the amount of cabling necessary for my little endeavor.  Basically here all then I would need would be a very short RS-232 combo RJ12 connection supplying serial com and a short RJ-45 connecion for the network pieces.
 
Looking some more it appears for use maybe of the RS-485 12VDC bus connection to a Somny electric shade connection?
 
Searching a bit here on the forum noticed that the HAI Email notifier board gets its power from the serial port and originally they did have some issues relating to the pinout of the serial cable to the board.  To me then this means that if it can drive the HAI Email notifier board then it should be able to drive my little microrouter.
 
I got mine today also.  It also looked as though it had been previously opened and installed.  I noticed the power connector on the board and called Worthington about it and they said it was 12vdc, so I connected a wall wart to it and the board gave off a little bit of smoke from one of the components near the rs-232 connector.  I called Worthington back and talked to someone else and they said that connector was for factory use only and it gets its power from the serial port.
 
A bit more on the barrel connection on the email board shows that it is an external power 5VDC connection rather than a 12VDC connection for external use and testing of the email board.
 
Edit: All boards were tested and updated with the latest firmware before they shipped. No need to update the firmware.
The 5V connector is not intended to be used with an Omni. It's intended to be used incase you are connecting to a different panel or maybe for some standalone applications.
 
Looking too at the email board it appears that J2 could be a TTL JTAG connection such that I could play a bit with the Omnifier board without a connection to the OmniPro panel via use of the 5VDC power port, JTAG, serial port and Network port.
 
omnifierboard.jpg
 
 
 
pete_c said:
Thank you Ral. 
 
This is where I am venturing to the unknown.  I was going to make up another RJ12 cable only connecting the 12VDC / ground pins to see what happens.  I am thinking that maybe the 12VDC is always present on said pins?  This is not a standard signal wire and appears to be some propietary thing with HAI.
 
That's interesting, Pete.  I guess the version of the OP2 manual I have is a little back-level as it does not show the +12V on pin 6. Found a newer version of the Leviton site that does have the diagram you posted.  I have seen some RS-232 PC cards with DB9 connectors that provide 12V power on unused pins, but I wouldn't say it is part of any standard.
 
I would guess that pin 6 is simply connected to the +12V supply.  With all power removed from the OP2, you could check with an ohm meter for a connection between pin 6 of the RJ12 and +12V AUX.  I wonder if the RJ12 is protected with a PTC or fuse.
 
I would guess that pin 6 is simply connected to the +12V supply.  With all power removed from the OP2, you could check with an ohm meter for a connection between pin 6 of the RJ12 and +12V AUX.  I wonder if the RJ12 is protected with a PTC or fuse.
 
Thank you Ral.
 
Baby steps here and trying to be innocous somewhat in what I want to try next.
 
Yup; as far as I know there is no known serial port standard that carries 12VDC on one of the 9 pins.
 
That said I am doing an NTP thing and using one serial pin right now that carries PPS (clock - Pulse Per Second is a method to fine-tune frequency and offset errors using NTP).  Documents state that the RS-232 signal should not be mixed with PPS and I am doing that and it works for me today.
 
IE: totally disconnect all power to the OPII panel and see if the two 12VDC connections are common. 
 
The new email board works with the old and new panel from what I can see so that 12VDC has probably been there a while.
 
Not sure though if HAI would have just used the same fuse or protection used for the Aux 12VDC output; I mean it is just a 12VDC output and it would have been less work.
 
Well now looking for a tiny TTL to RS-232 board without the RS-232 9 pin connector on it. 
 
Found it cheap (relatively) on Amazon and I think it will fit fine inside of the micro router.
 
I already have a tiny 12VDC to 5VDC board that fits fine inside of the device.
 
TTL-RS232.jpg
 
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