_yak technoblog

Interfacing with the control gateway Device CKOZ 00/03 we got an API from Moeller to communicate to their wireless dimmer actuators. The device offers a RS232/RJ11 connector or per default a USB one.

The USB connection however does not work on a COM Port but offers only standard USB HID connection. We needed a library to open up a connection to this USB Devices and talk to it. We used the Sourceforge LibUSBDotNet library for this ( http://libusbdotnet.sourceforge.net/ ) in an older version as described later in the belower forum entry. Problems arise not while connecting to a device but while finding and communicating with the right device endpoints. Here is a tutorial on how to do that:

- Read on FROM http://community.sharpdevelop.net/forums/p/7995/22800.aspx#22800 and take experimental source code from ttp://sourceforge.net/projects/xcom-hp
- Modify VID hex = 188A and PID Hex 1101 in Class USBPort
- Modify READ AND WRITE ENDPOINT in Class USBPort ,
since we get the Moeller endpoint ids from the helper tool  testlibusb-win.exe, we can see 2 endpoints
EP moeller 1 81h == 129  == READENDPOINT
P Moeller 2 02h == 2 == WRITERNDPOINT
From the Library LibUSBDotNet we see in class ReadEndpoints (start at 129 == 0×81 )and WriteEndpoints (start at 1), so it is clear which one has to be assigned
- in USBPort.openDevice() the lines device.SetConfiguration(1) and device.ClaimInterface(0) are crucial for working

When it all stopped working

Right the day after, the solution with the LibUSBDotNet Lib was not working anymore without a single code change tested on three Win XP PCs. The crucial line

[code lang="java"]device.SetConfiguration(1)[code] freezes the PC and requires a reboot to even close the application and reaccess the Moeller gateway once again. However the SimpleHID Write test application still could communicate to the Moller gateway. So set a broken device apart, we needed a new solution. We found the very handy Jan Axelson Lakeview Research - http://www.lvr.com/usb.htm that offers a bunch of resources to the USB topic.

With generic_hid_cs and usbhidio_V2.3.cs it offers free c# src for accessing generic USB devices. Both seem quite similar and are working with the obove Vendor and ProductID for our purpose. Finally this resolved the USB communication odyssey