Multisim Impedance Meter

[jreis]

I am a new user to multisim. I have the Analog Devices Addition. In a toy problem to gain familarity with the tool:

   When I short the input terminals to the Impedance Meter icon, as expected it measured essentailly zero. However, 

   When I then connect a ground to the shorted terminals, the multimeter indicates R= -49.9002 , X =0

Furthermore:

When I leave both terminals open,  the multimeter indicates R= -49.9002 , X =0

When I ground the + terminal of the multimeter, leaving the - terminal floating,  the multimeter indicates R= -49.9002 , X =0

When I ground the - terminal of the multimeter, leaving the + terminal floating,  the multimeter indicates R= -50 , X =0

When I connect a 1K resistor accross the terminals (neither terminal grounded) , the multimeter indicates R= 1000 , X =0

If I then add a ground the -  terminal of the multimeter, the multimeter indicates R= 950.1 , X =0

If the ground is moved to the + terminal of hte multimeter, the multimeter indicates R= -49.9 , X =0

I do not understand what is going on. It seems that the meter is not functioning correctly.

Your comments, insights, and suggestions are most welcome.

Thank you.

--jim

[jreis]

I have continued to try to figure out what's happening with the Impedance meter readings... using an Edisonian approach.

Findings:

1. If a 50 ohm resistor is inserted in series with the impedance + terminal, the meter reading is correct (it doesn't matter if the - terminal is grounded or not).
2. Place a resistor RL, one end connected to ground; then connect the Impedance Meter (as in #1 above) and it measures RL; Connect a 2nd Impedance meter with it's 50 ohm series resistor to RL ==> both impedance metersnow read 2RL
3. Add a 3rd Impediance meter with its 50 Ohm series resistor to RL and now all 3 meters read 3RL.
4. The same things happens with an arbitrary Z

Conclusion. From a meter measurement point of view, each additional impediance meter (with it's 50 series resistor) when added in parallel to a load, ZL, the measurements acts as if an additional load has been place in series with the original shunt! The measured values is Z(measured) = ZL*(number of parallel meters).

Now that's counter intutitive!

--jim