Hello.

1394 device's capable data rates are S100, S200, S400 and S800.
Each devices has multiple layer, and each layer's capable data rate
can be different.

For example, My product(Digital Camcorder) has PHY, LINK and 61883 Layer
and each layer's capable iso data rate is following.
- PHY : 400Mbps
- LINK : 400Mbps
- 61883 : 100Mbps (It complemented on IMPR(Input Master Plug Register))

When device is connected to PC(xp), PC read the three speed register.
But, windows xp(without no servicepack) send ISO data to device at 400Mbps

I expected windows xp will determine minimum data rate what device's layerhas.

So I did same test on window xp with servicepack 1, and 2
then, PC use 100Mbps.

Finally, my question is following.

1. Why windows xp(without any servicepack) use 400Mpbs to device witch has
100Mbps setting on 61883 IMPR?

2. What is the xp's rule to determine ISO data rate to device.

3. How about win98, win me, win2000 ?

Re: 1394 data rate for Isochronous trnasfer. by Bill

Bill
Tue May 31 21:30:20 CDT 2005


> So I did same test on window xp with servicepack 1, and 2
> then, PC use 100Mbps.
>
> 1. Why windows xp(without any servicepack) use 400Mpbs to device witch has
> 100Mbps setting on 61883 IMPR?

I am going to take a wild stab here and guess that this was a bug that was
fixed in XP SP1.

> 3. How about win98, win me, win2000 ?
>

I would be willing to bet that these will all get it wrong as they all came
out before XP SP1.

--
Bill McKenzie


"SmartMan" <SmartMan@discussions.microsoft.com> wrote in message
news:9D993FFE-FD1D-4BDC-A89F-B5F93E28AF34@microsoft.com...
> Hello.
>
> 1394 device's capable data rates are S100, S200, S400 and S800.
> Each devices has multiple layer, and each layer's capable data rate
> can be different.
>
> For example, My product(Digital Camcorder) has PHY, LINK and 61883 Layer
> and each layer's capable iso data rate is following.
> - PHY : 400Mbps
> - LINK : 400Mbps
> - 61883 : 100Mbps (It complemented on IMPR(Input Master Plug Register))
>
> When device is connected to PC(xp), PC read the three speed register.
> But, windows xp(without no servicepack) send ISO data to device at 400Mbps
>
> I expected windows xp will determine minimum data rate what device's
> layerhas.
>
> So I did same test on window xp with servicepack 1, and 2
> then, PC use 100Mbps.
>
> Finally, my question is following.
>
> 1. Why windows xp(without any servicepack) use 400Mpbs to device witch has
> 100Mbps setting on 61883 IMPR?
>
> 2. What is the xp's rule to determine ISO data rate to device.
>
> 3. How about win98, win me, win2000 ?
>