Answer
All the IVI drivers allow to switch off range checking as it is defined in the IVI standard (IIviDriverOperation interface).
Example for RsRtx:
RsRtx driver = new RsRtx("TCPIP::192.168.1.10");
driver.DriverOperation.RangeCheck = false;
Plain SCPI commands can be used as follows (See section "System" of the driver help file):
RsRtx driver = new RsRtx("TCPIP::192.168.1.10");
// Write command
driver.System.WriteString("*RST");
// Query command
driver.System.WriteString("SYST:ERR?");
response = driver.System.ReadString();
However, the recommended way is to use our utility functions (See section "Utility Functions" of the driver documentation):
RsRtx driver = new RsRtx("TCPIP::192.168.1.10");
// Write command
driver.UtilityFunctions.WriteToInstrument("*RST");
// Query command
string val = driver.UtilityFunctions.QueryString("*IDN?");