Protocol Differences - Keithley 2302 Instruction Manual

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 and SCPI protocols.
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:
1. 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
commands, 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?
2. When a query is sent, either the data must be read back or a Device Clear (DCL) or
Interface Clear (IFC) must be performed to reset the query.
3. When sending a command or query, do not attempt to read data from the power supply
until the terminator has been sent (usually Line Feed with EOI). Otherwise, a DCL or
IFC must be sent to reset the input parser.
4. When receiving data, all data, up to and including the terminator (LF with EOI), must be
accepted. Otherwise, a DCL or IFC must be sent to reset the output task.
5. Empty command strings (terminator only) should not be sent.
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
TestEquipmentDepot.com
488.1 Protocol G-3