Hello,every one!
I am designing the USB DEVICE interface which accords with the USBTMC and USB 488.On the visa test panel of the Measurement & Automation Explorer,I test the viread,viwrite, they
are all ok.But when I use visa read STB.vi in the labview to read the device status, it always prompt:"READ STB ERROR,the operation is timeout".
I understand the procedures between the computer and the device according with the USBTMC and USB 488 as follows:
1.the computer sends the command to the device
2.the device sends a service request by the interrupt endpoint when the outbuf is not empty.
3.the computer sends the read request to the device
4.the device sends data to the computer.
the data transfered between the computer and the device are as follows:
Dev Phase Data Info Time Cmd.Phase.Ofs
--- ----- ----------------------------------------------------- ---------------- ----- ------------------
1 DO 01 1c e3 00 - 06 00 00 00 - 01 00 00 00 - 2a 49 44 4e ............*IDN 0us 1.1.0
3f 0a 00 00 ?... 1.1.16
2 DI 81 d4 .. 49ms 2.1.0
3 DO 02 1d e2 00 - 00 04 00 00 - 00 00 00 00 ............ 2.1sc 3.1.0
4 DI 02 1d e2 00 - 18 00 00 00 - 01 00 00 00 - 54 6f 6e 67 ............ 20ms 4.1.0
68 75 69 2c - 54 48 32 38 - 32 36 2c 56 - 65 72 20 31 4.1.16
2e 30 2e 30
the computer sends "read STB" to the device as follows:
1.the computer send "read STB" packet by the control endpoint to the device;
2.the device gives a response to the computer by the control endpoint
3.the device returns the status byte to the computer by the interrupt endpoint.
the data transfered between the computer and the device are as follows:
1 CTL a1 80 07 00 - 00 00 03 00 CLASS 2.9sc 5.1.0
2 DI 01 07 00 ... 4.0ms 5.2.0
3 DI 87 50 .P 3.9ms 6.1.0
Dose anyone know why the "read STB" is error?please help me.thank you!
