Keithley 2303 - Protocol Differences

Models 2303 and 2303B GPIB 488.1 Protocol D-3
The following rules must be adhered to when sending this command with either parameter
setting:
1. The command must be the only command on the line or it must be the last command in
the command string.
2. No command or query can be after this command on a line going to the power supply.
3. After sending this command allow some time for the instrument to switch into the new
mode and be ready for new commands before sending another command or query.
For example, the following command strings are valid:
SYST:MEP ON
SENS:NPLC 1.5; :SYST:MEP OFF
The following command strings are invalid:
SYST:MEP ON; SENS:NPLC?
SYST:MEP OFF; VOLT 2.5
Changing the GPIB mode over the bus will clear the blinking R that indicates remote mode
operation.
Protocol differences
The following information covers the differences between the 488.1 protocol and the SCPI
protocol.
Message exchange protocol (MEP)
When the 488.1 protocol is selected, the MEP is disabled to speed up GPIB operation.
The following guidelines/limitations must be followed when using the 488.1 protocol:
• If a query is sent, it must be the only command on the line or the last of a multiple
command line (this limitation also means no multiple queries can be sent). Otherwise,
full SCPI command syntax is still supported including long-form and short-form com-
mands, multiple commands, and MIN/MAX/DEF parameter definitions.
For example, the following command strings are invalid:
:SOUR:VOLT?;*OPC?
:SENS:CURR:RANG?;:READ?
:READ?;:READ?
The following command strings are valid:
:SOUR:VOLT 4;*OPC?
:SENS:NPLC 1.0;:SENS:CURR:RANG MIN
:SENS:CURR:RANG? MAX
:READ?