hello,
I would like to use my USB MMC card reader can anyone here guide me how to work with it.
thanks

Put your card into the reader and plug it. Check if anything appears in /media . If yes, and it is mounted - OK, else it can appear but wait for you to just mount it. Else you need to compare dmesg output before and after (wait ~10-15 seconds) plugging. It should contain the device name (like sda or sdb), and possibly it can mention something like 'partition scan' and a device name like sda1 or sda5. Try running 'mount /dev/<last device name mentioned in dmesg output> /mnt/<whatever you want, but it must exist>' afterwards. If you have any problems, post last 50 lines of dmesg output after plugging the device.

pls see log after attching the card reader,my led status OK.

input: AT Translated Set 2 keyboard on isa0060/serio0
usb 1-2: new full speed USB device using address 3
usb 1-2: device not accepting address 3, error -71
usb 1-2: new full speed USB device using address 4
scsi1 : SCSI emulation for USB Mass Storage devices
Vendor: Generic Model: USB SD Reader Rev: 1.00
Type: Direct-Access ANSI SCSI revision: 02
SCSI device sda: 498176 512-byte hdwr sectors (255 MB)
sda: Write Protect is off
sda: Mode Sense: 03 00 00 00
sda: assuming drive cache: write through
/dev/scsi/host1/bus0/target0/lun0: p1
Attached scsi removable disk sda at scsi1, channel 0, id 0, lun 0
Vendor: Generic Model: USB CF Reader Rev: 1.01
Type: Direct-Access ANSI SCSI revision: 02
Attached scsi removable disk sdb at scsi1, channel 0, id 0, lun 1
Vendor: Generic Model: USB SM Reader Rev: 1.02
Type: Direct-Access ANSI SCSI revision: 02
Attached scsi removable disk sdc at scsi1, channel 0, id 0, lun 2
Vendor: Generic Model: USB MS Reader Rev: 1.03
Type: Direct-Access ANSI SCSI revision: 02
Attached scsi removable disk sdd at scsi1, channel 0, id 0, lun 3
USB Mass Storage device found at 4
[admin@serv admin]$

Try
mount /dev/sda /mnt/cardreader
mount /dev/sdb /mnt/cardreader
mount /dev/sdc /mnt/cardreader
mount /dev/sdd /mnt/cardreader

one-by-one. One of them will probably work... Others will report nonexistent devices.

Also sda1,sdb1,sdc1, sdd1...

I have a card reader too, and i have been unable to use it in a comfortable way.

Look what happens:

1) insert the card
2) dmesg reports nothing
3) i know the card address is sdc1, when i have no other usb device plugged.
4) pmount /dev/sdc1 data reports the error:
Errore: il dispositivo /dev/sdc1 non esiste
Error: device /dev/sdc1 doesn't exist
5) so i have to use:
pmount /dev/sdc data
mount: wrong fs type, bad option, bad superblock on /dev/sdc,
missing codepage or other error
In some cases useful info is found in syslog - try
dmesg | tail or so
6) and only now, using sdc1 ( used before ) the card reader works:
pmount /dev/sdc1 data

And it is mounted.

Really unhappy...