I'm working with an Arduino Due and four 5V TTL pressure sensors. I'm using this logic level converter to convert from the 3.3V Due to the 5V sensors. I've been having problems using all four at a time, so I broke out the oscilloscope and noticed a voltage level problem. When I have one device plugged in, logical low is ground. When I have two devices, it creeps up a bit. Three devices, it creeps up to around 2 volts. When I have all four devices plugged in, logical low is around 2.5 V, which is above the logical low threshold for the Due, and thus, nothing works. Does anybody have any ideas on how to fix this?
EDIT: forgot to mention, when I say "logical low," I mean on the TX line. The RX line is fine. EDIT 2: Added link to data sheet in the post instead of in the comment, and added more detailed schematic, if it helps. All sensors are hooked up the same way as the in the detailed schematic.
Here is a cartoon-y schematic:
Slightly more detailed schematic: