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2308-900-01 Rev. A / July 2008
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9-7
Model 2308 Portable Device Battery/Charger Simulator User’s Manual
Section 9: Measurement Commands and Optimizing Measurement Speed
read:amp?
' switch to the 5 A current range, trigger a pulse current
high reading and return it.
GPIB 488.1 protocol
Model 2308 supports two GPIB protocols: SCPI and 488.1. The 488.1 protocol significantly
increases speed over the GPIB.
When using the 488.1 protocol, throughput is enhanced for data sent to the power supply
(command messages) and for data returned by the power supply (response messages). The
speed of readings sent over the GPIB is also increased. Factory default is SCPI protocol.
With the 488.1 protocol selected, you will still use SCPI commands to program the power supply.
Operation differences between the two protocols are discussed below.
Selecting the 488.1 protocol
Perform the following steps to select the 488.1 protocol:
When switching between the SCPI and 488.1 protocol, the instrument does not reset. The GPIB
protocol setting is saved in EEPROM, and the unit will power up with that selected protocol until
changed again.
The GPIB protocol can be changed over the bus. If you use the following query to request the
state of Message Exchange Protocol (MEP), you will know which protocol is enabled:
:SYSTem:MEP[:STATe]?
If a “1” is returned, MEP is enabled, and the SCPI protocol is selected. A “0” indicates that MEP is
disabled, and the 488.1 protocol is enabled. To summarize:
1 = SCPI protocol
0 = 488.1 protocol
Send the following commands over the GPIB to change the GPIB protocol between SCPI and
488.1:
:SYSTem:MEP[:STATe] <1 or ON> Selects SCPI protocol
:SYSTem:MEP[:STATe] <0 or OFF> Selects 488.1 protocol
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.
NOTE
To optimize speed, the
read:amp?
command combines range changing,
triggering a pulse current measurement, and taking a reading. Note that in the
command sequence above, the trigger level was set to the 5 A range (using the
sens:pcur:sync:tlev:amp
command) before using the
read:hund
command.
NOTE
The 488.1 protocol is a bus-only feature - there is no front panel support.
Summary of Contents for 2308
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