Amp shunt common mode voltage

[mervg]

I am using a GRT hall effect sensor for my ammeter input.  When attached to a GP input it does not record in the log or be used in the calculation with the VPX.  I am thinking of designing a simple circuit to convert the sensor output to be used with the shunt amps inputs.  In order to do this I need to know the common mode voltage range and input current requirements (or resistance) of the amps shunt input to the ems?  Perhaps Dynon can comment on this as measuring the parameters in a flying aircraft is not so easy.

Merv

 

[dynonsupport]

The amps shunt input is pretty basic: 1mV for each 1A flowing through it. When the input sees 1mV the SkyView displays 1A. When the input sees 2mV, the SkyView displays 2A. Etc.

I am using a GRT hall effect sensor for my ammeter input.  When attached to a GP input it does not record in the log or be used in the calculation with the VPX.  I am thinking of designing a simple circuit to convert the sensor output to be used with the shunt amps inputs.  In order to do this I need to know the common mode voltage range and input current requirements (or resistance) of the amps shunt input to the ems?  Perhaps Dynon can comment on this as measuring the parameters in a flying aircraft is not so easy.

Merv

 

[mervg]

I understand the differential voltage. My question was related to using the EMS differential inputs at some voltage other than the 13-14V ships power, i.e. how low a common mode voltage can I use on the differential inputs. Dynon on an older thread wrote:

"On the D10/D12/D180, the amps shunt must have 6-30V on it relative to ground. Basically, it must be on a positive wire, not the ground wire. The EMS cannot read the output unless it has this "common mode" voltage on it.
SkyView does not have this restriction."

So just how low a common mode voltage can be used on Skyview EMS differential inputs? Does it extend close to ground? My other question is what the input current (or resistance) to the differential input pins of the EMS? Is it in the mA, uA or pA range (1k, 100k, 10M ohms) ? What I am looking to build is a simple resistive bridge to convert the output of the GRT sensor to the "shunt inputs" of the EMS.

Merv