I have recently purchased the MGL EMS-2 with an RDAC. I set it up on the bench so I could test senders and whatnot. The red X's were there from the beginning. What I did find was that you have to put at least ONE 120 Ohm resistor on one end of the CAN buss. (IF not both, but so far only one at the MGL end of the CAN buss for me.) Without the resistor you will always get the red X's. Since I'm installing in a Long EZ I have a longer CAN buss cable that is approx 10'. But, so far it works with the 120 ohm resistor at the MGL end. Looking forward to getting it in the plane.
One thing I did note was that you have to have the right Oil pressure sender from VDO. They do not put the resistance of the senders in the literature. That would be nice if they did that! I had to attach air pressure to run the VDO sender up and down and check the resistance of the sender. Otherwise, you have to go thru the whole proceedure of calibrating the sender with the unit. What a pain that is. I find that between 10 and 125 ohms from 0-100 PSI is the (Mostly) ideal range for the VDO 10 bar sensor that I have. Many of the VDO sensors I did find have resistances from 10-225 ohms and one started at 300 ohms and went down instead of up! Good thing I checked all this on the bench.