I'm using a modern NI USB-GPIB adapter with NI-MAX 19/488.2 to query an Agilent E8361A VNA with SCPI commands.
Commands such as
SENS:FREQ:START? -- basically any command ending in a question mark -- returns the proper string with no hiccups. The problem is that anytime I send a command such as
SENS:FREF:START 100mhz , the VNA sets the start frequency to 100 MHz but the VNA window displays the SCPI error -420 "Query Unterminated" and causes the NI-488.2 terminal to time out. I've tried setting the terminating character to CR, LF, and manually sending them both to no effect.
Any ideas how to eliminate those -420 errors? Thanks in advance for your assistance.