G-4 IEEE-488 and SCPI Conformance Information Model 6485 Picoammeter Instruction Manual
Selecting the 488.1 protocol
Perform the following steps to select the 488.1 protocol:
NOTE The 6485 must be set up to be remotely controlled over the GPIB to select the
488.1 protocol. SCPI language is the only language available over the RS-232
bus. To setup to use GPIB from the local measurement mode:
-Press the COMM button
-Using the or range keys, select GPIB.
-Press Enter to complete the change.
1. Press CONFIG (CONFIGURE: will be displayed).
2. Press COMM to access the communications menu. If a BAUD is displayed flash-
ing, the 6485 is configured to use the RS-232 bus. See Note above and change to
control over the GPIB.
3. Scroll using range key until LANG is displayed.
4. Press the cursor key to place the cursor on the currently selected language
(either DDC, SCPI, or 488.1 will be flashing).
5. Scroll using range key until 488.1 is displayed. To change back to 488.2, scroll
to the SCPI menu item.
6. Press ENTER to save the change.
When switching between the SCPI protocol, DDC protocol, and 488.1 protocol, the
instrument resets. The GPIB protocol setting is saved in EEPROM, and the unit will power
up with that selected protocol.
The GPIB protocol cannot be changed over the bus. However, there is a query command to
determine the presently selected protocol. When the 488.1 protocol is selected, the mes-
sage exchange protocol (MEP) disables. Therefore, if you use the following query to
request the state of 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
Protocol differences
The following information covers the differences between the 488.1 protocol and the SCPI
protocol.
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