using nest if then statements in ABM component

[jade.swordy]

I have a two input, 1 ouput circuit as in the schematic attached. My third node is defined at the bottom by the very high resistance voltmeter. What I have is a user-defined ABM current source that is dependent upon other parameters within the circuit. What I am wondering is this, is my conditional statement entered in the correct format? The conditions are particularly complex and outline as follows:

If the voltage difference between V2 and U1 is greater than 0, then the current in the ABM = 10^-12

If this voltage difference above is not greater than zero and if (V(1)-U(1))<(V(2)-U(1)), then the ABM current is (0.1*((-(V(2)-U(1)))^0.35))*0.00001596*(((V(2)-U(1))-(V(1)-U(1)))/2)*(V(1)-U(1))

Otherwise, if (V(1)-U(1))>= (V(2)-U(1)) then, the current is (0.1*((-(V(2)-U(1)))^0.35))*0.00001596*(((V(2)-U(1))^2)/2)

As you can see, these are very complex conditions and my concern is that I cannot simply type in U1 and get the compiler to understand that I want the voltage being read at the bottom-node voltmeter. I believe that I am using the correct nesting as far as the coding format is concerned: if(T,X,(if(Q,R,S))).

Any help would be much appreciated, and clarification can be provided.

[_user32 · Accepted solution]

I am not sure why its not throwing an error for the use of U(1), perhaps that's a valid reserved word.

If you want to reference a voltage correctly it should be V(net_name) for single ended voltages (referenced to ground) or V(net1,net2) for differential voltages... For ABM models I suggest turning on net visibility for the entire schematic so you know the net name at the positive terminal of U1 or any other location for that matter.

I think the syntax you have for if/then/else is correct otherwise.

Regards,
Pat Noonan
National Instruments

[jade.swordy]

And am I correct in that by differential voltage your mean that V(1,2) would be the voltage difference between node 1 and node 2 (1-2)? Just to check.

Thanks

[_user32]

jade.swordy,

Yes for the ABM a differential voltage is V(1,2) , meaning:  

V(1,2) = Voltage at net "1" - Voltage at net "2",

Example: Probe1 = +5V, Probe2 = -5V...

Regards,

Pat Noonan

National Instruments