Two questions:

1. is something known about a usb driver for epson receipt printer m129c?

2. which reasons ar possible for the message  "already running port x disabled 
by hub (EMI?), re-enabling...". Is it always electromagnetic interference?

The background of these questions: I managed an epson receipt printer m129c  
to work with kernel 2.4.20, but there are still some annoying failures which 
are related to this "EMI?" messsage.

I am interested in pathching these problems but I need some advice where to 
look at and what to do. Therefore I give here just a sketch of the problems I 
encountered; details can be deliverd as needed:

We have 3 IBM Netvista thin clients with kernel 2.4.20. To each thin client is 
attached via usb: mouse , keyboard, reader for magnetic cards, epson receipt 
printer m129c and (on 2 boxes only) an hp laser jet 1200.

In order to acces the receipt printer, I had to do some nasty trick: I took 
the printer driver of kernel 2.4.18 and added an entry 
USB_DEVICE(0x4b8,0x202) to the usb_lp_ids array. (This trick did not work for 
the printer driver of 2.4.20)

This solution works since 7 weeks and I noticed two things: First, the daemon 
which listens to the magnetic card reader lost its connection to the device 
sporadically and had to be restarted. (this phenomen can be simulated as 
follows: pull out the cable of the card reader and plug it in again; the 
daemon has the correspondign device (ttyUSB0) still open, but does nat 
receive any input; do restart the daemon, on has to stop the daemon, make a 
"cat < /dev/ttyUSB0" and then restart it)

Second I noticed in th log messages sporadically messages like

Feb 20 13:58:08 kasse1 kernel: hub.c: already running port 4 disabled by hub 
(EMI?), re-enabling...

On two systems the corresponding device is the receipt printer, on one system 
it is the laser printer.

The occurrence of these events may be cuased be electromagnetic interference 
(lights switched on or off).

Since two days we have massive problems with one system (which is located in a 
different room than the other two): This EMI-message occurs more often (now 
every 5 to 10 minutes) and sometimes the usb system does this reenabling over 
and over again without pause until the printer is powered off. When the 
printer is powered again its error led blinks. To convice the printer to 
work, we found the following annoying procedure: stop printer daemon, printer 
power off, remove usb-cable, printer power on, plug usb-cable in, kill 
processes having this device opened (sometimes this power off - on play has 
to repeated till all processes are killed), make "cat /proc/bus/usb/devices" 
and then the printer works again.

Do you have any idea? Is this really an EMI-problem or is it a problem of 
the proprietary usb interface of the printer:
T: �Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 68 Spd=12 �MxCh= 0
D: �Ver= 1.10 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 8 #Cfgs= �1
P: �Vendor=04b8 ProdID=0202 Rev= 1.11
S: �Manufacturer=EPSON
S: �Product=EPSON UB-U01II/02II
S: �SerialNumber=20020402144209440M11J
C:* #Ifs= 1 Cfg#= 1 Atr=c0 MxPwr= �0mA
I: �If#= 0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=02 Driver=usblp
E: �Ad=01(O) Atr=02(Bulk) MxPS= � 8 Ivl=0ms
E: �Ad=82(I) Atr=02(Bulk) MxPS= �64 Ivl=0ms

Addendum: Interrogation of the people working in this room brought the 
foolowing evidence: Since two or three days there is an electric light in 
this room flickering. After shutting down this light the occurence of this 
"EMI"- message dropped to a normal level.

But there is still the problem that reawakening the printer is a little bit 
tricky after some communictaion problems occur.

Best regards,

Ludwig Balke
-- 
Dr.Ludwig Balke
Johann-J�rgen-Str. 15
91052 Erlangen
Tel. 09131/407 368
Fax. 09131/129 297



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