VIAS USB data format

[Liquid_Crystal]

Trying to use an Analog Devices  AD5535 evaluation board communicating via the their SDP-S USB com board. ( The SDP-S is a daughter board on the eval board ).

The AD5535 wants 5 bits of channel address date and 14 bite of voltage data written to its input register.

Any suggestion on how to format the data into a 19 bit data word then pass it via a VISA write to the USB port?

Thanks

[psuedonym]

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@Liquid_Crystal wrote:

Any suggestion on how to format the data into a 19 bit data word then pass it via a VISA write to the USB port?

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You won't be able to use VISA for this.

[rolfk]

Analog Device doesn’t document the USB protocol used for this interface so you can’t communicate to it through VISA as already pointed out. Even if they documented the protocol you would not want to implement that over VISA as implementing a USB protocol is very cumbersome and VISA has certain limitations that does not allow certain USB features that might be required for high performance streaming devices like video or sound devices.

Instead you want to use their SDK and investigate the interfaces it has. Possible options could be a .Net interface (can be hard to understand but once you do LabVIEW gives you the tools to access it without to much worries about pointers, memory allocations and such) or a DLL through the Call Library Node (often equally hard to understand such APIs but use of the Call Library Node by people not Knowing C programming is a disaster waiting to happen as you need to know quite a bit about memory pointers and memory allocations in order to get this working rather than creating an app that crashes randomly (or even worse).

[psuedonym]

While searching for something else, I came across this : http://www.ni.com/tutorial/4478/en/#toc2

which may be useful for you.

[rolfk]

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@psuedonym wrote:

While searching for something else, I came across this : http://www.ni.com/tutorial/4478/en/#toc2

which may be useful for you.

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Well that would be USB Raw communication. For this to work you need to know the USB data protocol used and I haven't seen anywhere documentation about that. Noticably there isn't any Linux support for this device either which is another indication that AD wants to keep this tech proprietary and hasn't released any protocol specification.

[psuedonym]

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@rolfk wrote:

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@psuedonym wrote:

While searching for something else, I came across this : http://www.ni.com/tutorial/4478/en/#toc2

which may be useful for you.

---

Well that would be USB Raw communication. For this to work you need to know the USB data protocol used and I haven't seen anywhere documentation about that. Noticably there isn't any Linux support for this device either which is another indication that AD wants to keep this tech proprietary and hasn't released any protocol specification.

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I did not delve in-depth into the Analog Devices documentation  - 1 minute max. Offering it as a possibility if it is use-able; the OP will have to determine that. 

.

[rolfk]

The according schematic shows that the SDP-S board is basically using the FTDI2232HQ chip. So it would be possible to access this interface through the FTD2XX DLL but you will have to then figure out how to configure the I2C or SPI interface to communicate with the desired serial bus interface of your chip.

I would not attempt to redevelop the FTDI driver on top of NI-VISA, as much as that might be an interesting project in terms of geek factor. Also the I2C and SPI interfaces aren't quite controllable through the Virtual Communication Port interface that the FTDI also supports when you install their VCP driver instead of the FTD2XX driver, but is meant for the use of the RS-232, 422 and 485 operation modes of those chips.

[Liquid_Crystal]

Thanks all for your suggestions.

I was hoping to interface the AD5535B with our well healed LabView test bed but it looks like another approach is warranted.

Thanks again!