Usbtmc Communication Overview; Use Usbtmc To Communicate With The Product - Fluke Calibration 5560A Programmer's Manual

USBTMC Communication Overview

USBTMC features these endpoints for communication:
• Use Control Endpoint to send standard, class, and vendor-specific requests to the Calibrator.
• Use Bulk Out Endpoint to send USBTMC command messages to the Calibrator.
• The Calibrator uses Bulk In Endpoint to send USBTMC response messages to the controller.
USBTMC-488 adds an additional endpoint called the Interrupt IN Endpoint. The Calibrator uses the
interrupt IN endpoint to send notifications (such as SRQ messages) to the controller. The interrupt IN
endpoint is also used for serial poll requests of the Calibrator. See the Universal Serial Bus Test and
Measurement Class and Universal Serial Bus Test and Measurement Class, subclass USB488
specification for more detailed information.
The USBTMC488 interface implements a full Remote/Local state machine for USBTMC
communication. See the IEEE-488.1 standard section 4.8.2.

Use USBTMC to Communicate with the Product

For the Calibrator to communicate with the USB device, Fluke Calibration recommends that you use
NI-VISA drivers.
NI-VISA requires a resource string in this format to connect to the correct USB instrument:
USB0::0x0F7E::0x800A::[serial number]::INSTR
Where:
• 0x0F7E: The Fluke vendor ID
• 0x800A: The Calibrator model number (5560A, 5550A, or 5540A)
• [serial number]: The serial number of the Calibrator. The serial number is also on the rear panel or
by use of the *IDN? command on one of the other remote interfaces. You can also find the serial
number with the Setup > About menu.
• INSTR: Use the USBTMC protocol.
To ensure the most efficient use of the Service Request (SRQ) mechanism provided by
USBTMC-USB488, first check that the RQS bit in the Status Byte is clear. To do this, perform
a serial poll of the Calibrator before you send any commands that could generate SRQ events.
This only needs to be done once in your program/procedure.
Check communications can be established:
Write *IDN?
Read the response
Clear registers and read the status byte:
Write: *CLS;*RST
Write *ESE 0
Write *SRE 191
Read the status byte (Serial POLL)
Before you proceed, set the event and status registers as required.
Note
Calibrator
USBTMC Interface
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