Interacting with an other USB device.

Hello,

I have a question. I have a USB Controlled device that I want to control with my Arduino Uno in place of my pc.
But I don't know how...
The manual says:

Packets for the K8090 are 7 bytes in size. Each packet is delimited by the STX (04h) and ETX
(0Fh) bytes. Validity of the packet can be checked by verifying the checksum byte (CHK).
8 bits
STX (04h)
CMD
MASK
PARAM1
PARAM2
CHK
ETX (0Fh)

But how do I send this with my Arduino to that device??

Thanks,
Lars

Which USB device are you trying to interact with? Some USB devices, like the Arduino, are slaves. Some are hosts/masters.

Slaves can not drive/control hosts. For that, you need a USB Host shield (and a boatload of talent and a bit of luck to write a driver).

I am trying to control a relay card. The k8090.
The instructions are given but I don't know how to connect and send it.

That, too, is a USB slave. Two slaves are not able to communicate. You need a USB Host shield.

And then?

And then?

(and a boatload of talent and a bit of luck to write a driver).

There is a USB Host library that might be useful. It’s Google time…

Larssie112:
I am trying to control a relay card. The k8090.
The instructions are given but I don't know how to connect and send it.

USB is a layered protocol. The packets you show are payloads on top of transactions which are carried by a link layer communicating over the physical layer. It isn't a straight forward process to send those few bytes by themselves.

You have a significant effort in front of you. You are probably better off skipping the USB part of the card and controlling the device directly.

You would probably be better off just hacking the board and wiring it to arduino digital output pins. Here is a assembly manual with schematic on page 10. If you remove the controller chip from it's socket, you could access the pins needed to directly control the relays. You could even utilize the switch inputs by reading the two switch arrays with two analog input pins if you wished.

http://www.vellemanprojects.eu/downloads/0/illustrated/illustrated_assembly_manual_k8090.pdf