On 10/09/2014 10:12, Paul Corfield wrote:
On Tue, 9 Sep 2014 23:44:13 +0100, David Walters
wrote:

On Tue, 9 Sep 2014 13:00:11 +0100, Roland Perry wrote:
And with Oyster there's at least the chance that you can see your
balance disappearing, if you know exactly where to look on a gate for
the fraction of a second it displays the number. I'm quite sure there's
no such facility for the contactless cards.

I'm a member of the contactless pilot and on my journey home this
evening both gates gave me red lights while opening but the exit gate
also displayed my fare. I've just checked the online version and that
is matching what I expected to pay and what was shown on the gate.

I'm not really sure how that happened. I'll have to look more closely
at the displays next time and perhaps try and get a picture.

Hmmm interesting. I wonder if TfL have responded to the trial
feedback about people not liking the absence of the fare to the paid
being shown on the exit gate display.

It suggests (I'll put it no more strongly than that) that something is
written to the bank card. I cannot see how else an exit gate could
calculate and display a fare within the few hundred millisecond
processing time parameter. I can't see there being contact with the
"back room" system in that time parameter.


Paul,

the current generation of CPC (aka EMV) cards can't be written to by the
'transit application' in the gate or validator, but they are updated by
the reader. They contain a transaction counter and a cumulative sum
recording the contactless transactions. If either of these reach a set
threhold then the card will require a Chip'n'PIN transaction so that it
can go online and ge tthe counters reset. This is a design feature to
minimise some of the risks if the card is lost or stolen.

If all you do is buy a coffee at Starbucks (or whatever), then the
occasional Chip'n'PIN operation won't be a problem. IN the transit world
I'm not 100% sure whether the card can go on for ever, or whether you
will need to buy a coffee every so often.

Future generations of EMV cards will have 'transit sectors' so that they
can carry tranit-related data.

With ITSO cards there is a lot of capability - depending on the
technical product (IPE in ITSO speak) - to store data on the card. A
Stroed Travel Rights IPE (TYP 2) is very like an Oyster APYG, and can
maintain a number of counters and accumlators on the card. Other IPE
TYPs are used for singles/returns and season/period products. But there
does seem to be a move at present to use the card - whether EMV or ITSO
- as just an ;entitlement to travel' token, with the cost of travel
being worked out in a commercial back office after the travel has taken
place.

I could go on and on about this, so if you have any more specific
questions I'd be happy to take them via private email.

Time to get off my hobby horse...

Kevin