I suggest you instead use the new "Electrode Validator" tool in the top of the right-hand panel in VNL:
- In Builder, use the "Split device" icon to split the device into centralregion + 2 electrodes.
- In Scripter, setup a calculation for one of the electrodes (or both electrodes if they are different).
- Run the calculation (which is real fast).
- On LabFloor, use the Electrode Validator to check if the electrode size is OK.