amulet display rs232 5v power connection from sbrio 9607

[tetego]

Hi,

I am trying to connect sbrio 9607 to amulet display using RS 232. Amulet display needs 5 V which I plan to supply through RS232 connection directly from sbrio. I also have NI 9697 RMC card attached to the sbrio and it has DIO connector which has 5V in its 49 and 50 pins. However this voltage is read with respect to digital ground. RS232 connector on Sbrio 9607 has its own ground pin (supposedly analog ground). When I read the voltage between DIO 5V and RS232 ground it reads 10V. I can as well find another pin from RMC card but what is the best solution for carrying 5V to Amulet Display  from Sbrio 9607 through RS232? I need to keep GND TX and RX pins of the RS232 intact whereas pin 1 for example can be used to carry 5V from sbrio. It seems that I have an analog -digital ground problem here. Any suggestions?

Thanks in advance.

Engin

[Sam_Sharp]

How much power does the display require? I don't expect that the sbRIO can provide much current from the digital I/O pins (3mA according to the datasheet). RS-232 is a communications port/protocol - it doesn't supply current to power devices.

Is there a USB port on the sbRIO? This should be able to provide a maximum of 900mA @ 5V.

[tetego]

Thanks Sam,

Amulet requires 300mA@5V. In my case RS232 is only a cable between two devices as long as I supply what they need at each end appropriately.

There is a USB port in Sbrio 9607 but I dont want to use it since i will need it for some other tasks.

Engin

[Sam_Sharp]

Ok, looking at the datasheet it seems like you can supply up to 1.5A from the 5V supply on the RMC connector. Wire up the 5V and GND terminals on the mezzanine card to your Amulet and then connect up the RS-232 cable and it should work.

The reason for mentioning RS-232 is that a standard DB-9 connector used for serial ports does not carry power. Of course, a 9-way cable can carry any signals/power (rated to the cable) but a serial port on a computer will not be able to supply much current (and doesn't have a 5V pin...RS-232 is +/- 15V).

[tetego]

I have to make a correction on what I have read. It seems that I was measuring the voltage between 5V from DIO and incorrect  pin in RS232 port of sbrio. The voltage between 5V

DIO and RS232 ground is as expected 5V. I hope to run the Amulet display soon.

Thanks