NI-VISA 15.0 Help Edition Date: June 2015 Part Number: 370131S-01 » This topic explains how to communicate with your USB device using NI-VISA. Recall that there are two classes of USB devices. The communication method depends on the device class. USB INSTR Class (USBTMC) Devices that conform to the USB Test and Measurement Class (USBTMC) use the NI-VISA USB INSTR class. These devices use 488.2-style communication. For these devices, use the VISA Open, VISA Close, VISA Read, and VISA Write functions the same way as if communicating with GPIB instruments. The following figure shows a LabVIEW VI that communicates with a USBTMC device.
Hi, last week I make one labview program for read with serial port the temperature sensor. This program is ok, and running (I used serial port of. Connecting Instruments via USB. 3 Learn LabVIEW. If your device does not have a serial number, NI-VISA automatically assigns a VISA.
Sound Museum Towa Tei Rar. In this example, the VI opens a VISA session to a USB device, writes a command to the device, and reads back the response. In this example, the specific command being sent is the device ID query. Check with your device manufacturer for your device command set.
After all communication is complete, the VI closes the VISA session. USBTMC LabVIEW Example Block Diagram USB RAW Class Communicating with the USB RAW class is more complicated, because each device may use its own communication protocol. Contact your device vendor for details about the device communication protocol. USB communicates using four types of pipes or endpoints: control, bulk, interrupt, and isochronous. Each type of pipe transfers a different type of information. Also, any number of endpoints can be of any endpoint type.
Think of an endpoint as a communication socket. For specific details about USB architecture, review the.
NI-VISA supports three types of USB pipes: control, bulk, and interrupt. When NI-VISA detects your USB instrument, it automatically scans your instrument for the lowest available endpoint for each type. When VISA detects the lowest available endpoint, it assigns that value to the appropriate VISA attribute. The bulk in endpoint and bulk out endpoint are stored in the and attribute, respectively. Synergy 1.3.7 Download. The interrupt in endpoint is stored in the attribute. A value of –1 indicates a USB device does not support that type of pipe. For the control pipe, only endpoint zero is supported.
If you are using the C API, use the function to change endpoints. In LabVIEW, use a Write VISA Property Node. NI-VISA includes four functions to transfer data through USB pipes. Before you can communicate with your device using these functions, you must set up the communication protocol using the VISA USB attributes. The following functions are available: • Use VISA USB Control In and VISA USB Control Out to transfer data using the control pipe.
Hi, I am a new poster here; I have been using Labview for about a year. I have a new USB-Serial converter that I cannot get VISA to see.
• To transfer data using a bulk pipe, use VISA Read and VISA Write. • If you are using LabVIEW, VISA includes an additional function to use the interrupt pipe: VISA Get USB Interrupt Data. In the C API, you can do this by accessing the and attributes of the event object. To write an interrupt pipe out to a device, you first need to set the VI_USB_BULK_OUT_PIPE attribute in the C API or use the VISA USB Raw Out Pipe Property Node, shown below, in LabVIEW. Then, perform a VISA Write. VISA USB Raw Out Pipe Property Node.
Quote: As I said in the post above, I used the block that MBED offer users to read and write data, via serial port. But these blocks have one mistake, if you put it in a loop. Normally, applications require readings every step in a loop. So, in this cases, if the baud rate selected is not very high, it works perfectly, but the problem appears (in my case) if I increase the baud rate over 38400 bauds.
Because the ports can´t be configured once each step. That´s why my program broke and LabView hang up. I would like to upload the blocks that I used in my LabView program, but I only can upload C++ programs from my compiler. So, I will just say the way to design your LabView program correctly.
Quote: You only need tree blocks: - Configuration block: in this block you have to put the 'VISA Configure Serial Port' block (offered by LabView), with which you will be able to configure the Baud Rate and other communication parameters. Furthermore, another block that you need is the 'VISA Set I/O Buffer Size Function' block, that will be useful if you need an in/out buffer to receive or to send the data. - Read block: in this block you only have to put the 'VISA Read Function' block and configure it. - Write block: in this block you only have to put the 'VISA Write Function' block and configure it. Only the 'Configuration block' has to be out of any loop. A good way to program would be starting putting the 'Configuration block' at the start of your LabView design, and then the loop with every Read or Write block inside. Best regards and enjoy your MBED!!
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