RDAC RPM WITH DUAL PMAGS

[RYAN21P]

I am hoping someone here could chime in with some settings or something. I have a dual PMAG installation, the units I have spit out a 2 pulse per revolution signal at 12v. They include a diode to install between pin 6 and pin 1 to drop voltage to 5v. I have the RDAC set up from the efis at 2 pulses and I have played around with the dip switches etc. No matter what I have the pulses set at or any dipswitch combination the RPM either reads about twice the value or zero. When it does read something it seems to drop closer to the real value for a split second every few seconds or so. I am not an expert in avionics whatsoever FWIW

[rainier]

Are yo saying there is no difference to the RPM displayed regardless of the number of pulses per revolution setting in the EFIS ?
I am assuming you have connected to RPM1 and are using the RPM1 menu in the EFIS ?

You can use 12V pulses with the RDAC no problem - no reason to drop to 5V. The RDAC is quite OK to 100V or more...

[RYAN21P]

Just seeing this! Yes to your questions. I am using rpm 1 in the menus. And that is the case, that no matter what I set the pulses to it reads about double. With the diode installed it reads zero so the 12v signal is when it reads double the rpm give or take. I purchased a oscilloscope and checked the signal to the rdac. The signal appears to be pretty clean. Even tried the opposite ignition source. Thanks!

[RYAN21P]

Just wanted to update this post. I have resolved the issue with rpm readings. So I’ll list my settings for those that are using mgl rdac xg with a dual Pmag ignition setup. All rpm dip switches on rdac are “off” rpm 1 on efis set to 1 pulse per revolution. I had to use eicad program from emag and wire to the ignition via a usb to serial adapter and configure the ignition to 1 pulse per revolution. I also removed the diode to revert the signal back to 12v per MGL. Problem solved. I’m fairly certain there’s a software glitch within MGL that caused all this. I should have been able to set the rpm 1 pulse setting to 2 and that “should” have worked. However it would only display the correct reading momentarily for about 1/2 second every 7-8 seconds or so then revert back to double the reading. Hope this helps someone.

Late update. on first flight had really bad cht readings and ultimately discovered that the above mentioned RDAC was actually faulty. Replaced entire unit on my own accord and everything was operational, including the rpm sensor without the above work around.