Preventing DIO from driving output high on power-up

[Blair_Hogg]

We are using the AT-MIO-16DE-10 with 3 8 bit DIO ports. When the system is first turned on, the DIO ports are rest to input ports. The system interprets this as a high output and turns everything on. The DIO ports drive relay cards which currently have a 47k resistor from the input to ground, a 10k resistor to a 2N7000 MOSFET switch which turns on the relay coil.

The DIO ports are acting like they have a pull-up resistor. The 47k resistor was recently added and has helped somewhat, but I don't want to go too low.

Any suggestions?

[Filipe A.]

Blair;

The startup state level of the digital lines of any E-series board is high impedance state. So, either there is something wrong with the board itself or the external circuitry you are hooking up to the board is doing something that is changing that behavior of the board.
I advise you, first, to hook up a scope to the digital lines to double check if the board, without being connected to any external hardware, is behaving like that or not. By doing that, you will be able to narrow the problem down to its cause.
Hope this helps.
Filipe