Experimental Physics and Industrial Control System
On Apr 18, 2013, at 5:12 PM, Andrew Johnson wrote:
Hi Mark,
On 2013-04-18 Mark Rivers wrote:
I don't have a serious need for this device, but there is an EPICS
user at
NIH, Andrew Gomella who needs to control 18 of the model 3006
devices,
which he is planning to do from a single Linux box.
Is this possible, even in kernel 3.8?
It should be possible even with your kernel version. The issue that
Guy
described is that the driver can only talk to one *type* of device
at once; so
as long as all 18 are the same model 3006 with the same product ID
he should
be fine.
Not quite what I meant - the ftdi_sio module can handle a mixture of
devices
from those device types it has compiled in, and ONE additional
vendor:product
combination passed as an option.
The other question is whether it provides a serial number attribute
that can
be used in a udev configuration file to ensure that the /dev/ttyUSB*
nodes
always map to the same physical devices. If there is no such
attribute then
unplugging 2 devices and plugging them back in could cause the
mapping to
change, which could be disastrous. Of course managing all 18 units
and
replacing them with spares still becomes a rather complicated chore.
If it doesn't provide a serial number he's in big trouble! I think
that the order
in which USB ports are scanned is deterministic, so as long as he
doesn't unplug
or replug a device the mapping might stay constant - but I wouldn't
like to rely
on it!
Guy
- Andrew
--
It is difficult to get a man to understand something, when his salary
depends upon his not understanding it. -- Upton Sinclair
- References:
- Linux USB serial questions Mark Rivers
- Re: Linux USB serial questions J. Lewis Muir
- RE: Linux USB serial questions Mark Rivers
- Re: Linux USB serial questions Andrew Johnson
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