WebUSB limitation controlTransferOut? - google-chrome

Question

I used usbmon to analyse usb packets, and implement it in webusb however I wasn't able to find a solution for this. This is what Sane send to usb :
S Co:1:074:0 s 02 01 0000 0081 0000 0
C Co:1:074:0 0 0
S Co:1:074:0 s 02 01 0000 0002 0000 0
C Co:1:074:0 0 0
Which is similar to a controlTransferOut() command, with requestType=Standard, recipient: 'endpoint', request: 1, index: 0x00, value:129
The 'value' here is very tricky since all other parameters should be correct according to documentation, however sending value:129 should send something like :
S Co:1:074:0 s 02 01 0081 0000 0000 0
However what I got instead is :
Uncaught (in promise) DOMException: The specified endpoint number is out of range.
While value is an unsigned short, which is max 0xffff ! So obviously value should be 0, and next nibble 0x0081. My question is how to trigger a Control Output (Co) with value in second nibble ?
The code is something like this :
navigator.usb.requestDevice({ filters: [{ vendorId: 0x1083}] })
.then(selectedDevice => {
device = selectedDevice;
return device.open(); // Begin a session.
})
.then(() => device.selectConfiguration(1))
.then(() => device.claimInterface(0))
.then(() => device.controlTransferOut({
requestType: 'standard',
recipient: 'endpoint',
request: 0x00,
value: 129,
index: 0x00}))
All other combinations are sent with response "Stall" for example (class, interface : 21 - vendor, device : 40 ...etc).
Device description and Endpoint descriptor are available here
Thank you

Answer 1

Just found it, request should be :
device.controlTransferOut({
requestType: 'standard',
recipient: 'endpoint',
request: 1,
value: 0,
index: 129})
This give :
S Co:1:075:0 s 02 01 0000 0081 0000 0
C Co:1:075:0 0 0
Which is exactly what I need.