Playing with a couple of these and discovered something which may cause a problem. All three types have an ‘accumulated driving timer,’ this adds all your driving time together and gives you an indication as to when your 45 minute break is due. There is also an ‘accumulated break timer,’ this adds all your breaks of 15 minutes or greater together. So far so good.
The problem is that the units will count both break and period of availability and count them together as break. As the vehicle unit gives a warning at four and a half hours driving. Let’s say you do 2:45 driving then you have 30 minutes POA then do an hours’ driving and then have 15 minutes of break, after which the ‘accumulated driving counter’ will reset and ‘allow’ you to do another 4.5 hours. You have now committed an offence 'cos you have actually done 8 hours 15 minutes driving with only 15 minutes break. The bloke from VOSA is going to be very interested when he looks at the card / vu download. 
Don’t blame the vu manufacturers; this way of counting time is in the Regs (1360/2002).
Best thing we can do is keep hold of the ‘Hours Guards’ timers and stopwatches etc and be very careful using the 4.5 hr timer on the digi tachos
Or ignore POA altogether and just use Break and Other work. 
I ignore poa , never booked it and i never will . Whilst i,m in company uniform i,am at work , simple .
This is something the FTA picked up on a few months ago, and stressed the need to ensure proper training is given to drivers to ensure they don’t rely on the counters. Any POA over 15 minutes is counted as a break - so you will end up breaking the law if you rely on the machine!
What is all this POA stuff then ■■? Drive, break, sleep … I thought thats all I did?
Im the same as Paul, Im at work and want paying for it all. I also want to be paid for 60 hours if I do 60 hours 
Another problem with the digi tacho is timing…i read this week that the tachos will use the same timing as aircraft…which is GMT…which is ok for half the year …but the rest of europe will have a problem calculating the time cos they are 1 or 2 hours ahead of us…and will constantly have to keep updating the clock…
anyway i havnt got a digi card and dont want one …and will not send off for one if by chance my bosss upgrades the fleet…then he can pay for my card …cos im not.. and my tacho at the moment works on these principles ...drive mode ...then bed mode ..thats it really..poa ..and abcs or whatever theyre called wont get a mention…
Wheel Nut:
Im the same as Paul, Im at work and want paying for it all. I also want to be paid for 60 hours if I do 60 hours
You should be paid for POA anyway. Problems may arise if you don’t book POA as POA when you end up 3 weeks short of the end of the reference period and have used all your hours, is your boss going to pay you to sit at home because that is all you will legally be able to do.
Anyone who works for a company doing poa and not gettuing paid must either be stupid or probably an immigrant willing to please theior boss.
I get paid a salary so it doesnt matter what hours i do the pays the same.
Wheel Nut:
Im the same as Paul, Im at work and want paying for it all. I also want to be paid for 60 hours if I do 60 hours
you should be getting paid for poa anyway. im paid from the minute my tacho is put in excluding the lunch break even if i sit on poa for 6hrs of the day