AFIK an EPG-scan will only be made with a card, that is "idle". So if
you want an EPG-scan, you will have to put in another DVB-card or switch
to every channel for a few seconds=scanning manually.
According to VDR's manual that is wrong:
EPG scan timeout = 5
The time (in hours) of user inactivity after which the
DVB card in a single card system starts scanning channels
to keep the EPG up-to-date.
A value of '0' completely turns off scanning on both single
and multiple card systems.
Yes...I must be wrong. But I never had VDR running for longer than 2
hours without a key-press...I just can't resist pressing all those nice
buttons...