User manual

2400 Series SourceMeter
®
User’s Manual GPIB 488.1 Protocol G-5
Trigger-on-talk
Trigger-on-talk functionality has been added for the 488.1 protocol. If a query has
not been received by the instrument, the SourceMeter will automatically assume a
READ? command has been sent when it is addressed to talk. This technique
increases GPIB speed by decreasing the transmission and parser times for the
command.
Trigger-on-talk is extremely useful in the single-shot reading mode (*RST default)
and is the main reason for a >2x speed improvement over the SCPI protocol.
Remember that the output must be on (:OUTput:STATe ON) before you can take
readings.
The ARM:SOUR BUS and ARM:COUN INF commands are not supported by
READ? with the 488.1 protocol selected. If you send one of these commands, a
DCL or IFC may be required to reset the GPIB.
Message available
The MAV (message available) bit in the Serial Poll byte will be set when the query
is finished being processed, not when there is data available in the output buffer
(as with the SCPI protocol). For the 488.1 protocol, output data will not be format-
ted until the first request for data is received. This delay may cause unexpected
time-outs when using SRQ on MAV for queries that take a long time to execute.
General operation notes
• The TALK, LSTN, and SRQ annunciators are not functional in the 488.1
protocol. This speeds up data throughput greatly. The REM annunciator
still operates since it is critical to fundamental GPIB operation.
• If the unit is in REMote, the GTL command may not put the SourceMeter
into the local mode. Only the front panel LOCAL key is guaranteed to oper
-
ate, if not in local lockout (LLO). GTL will still disable LLO.
• IEEE-488 bus commands and features (GET, IFC, SDC, DCL, LLO, Serial
Poll, and SRQ) are still fully supported.
• Multiple TALKs on the same query are supported as in the SCPI protocol.
This feature is useful when reading back long ASCII strings.