How to setup clock and calendar for canon p23 dhv? Thanks

There are no parts listed. You would have to contact Canon Service Centre direct. Or someone who does 3D printing could make one.

https://www.google.com/search?q=Canon+P23-DHV+replacement+paper+cutter+strip

https://www.google.com/search?q=Canon+P23-DHV+replacement+parts

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See the instructions at the beginning of the manual: http://downloads.canon.com/cpr/software/calculator/P23-DHV-(USA-HWB).pdf

P23-DHV:
http://downloads.canon.com/cpr/software/calculator/P23-DHV-(USA-HWB).pdf

P23-DHV G:
http://www.usa.canon.com/app/pdf/calculator/P23-DHV_G_USA_GB.pdf

The calendar and clock setting section is the first thing in the user guide at
http://downloads.canon.com/cpr/software/calculator/P23-DHV-(USA-HWB).pdf

Canon P23-DHVInk roller Part# IR40T

http://www.gorillapaper.com/ink-roller-ir40t-b-r.html
Thank you

Follow the illustrated instructions in the manual available at the manufacturer's web site
http://www.usa.canon.com/consumer/controller?act=ModelInfoAct&tabact=DownloadDetailTabAct&fcategoryid=346&modelid=15431

Press and hold the ClockDate Set button for three seconds until the display shows the date with the first digit blinking. Enter a two-digit month, a two-digit date, and a four-digit year, followed by the ClockDate Set button.

Press and release the ClockDate Set button. Press and hold it for three seconds until the display shows the time with the first digit blinking. Enter a four-digit time, press AM/PM as appropriate, then press the ClockDate Set button. Press CE/C to finish and return to calculation mode.

You can download a copy of the manual from the manufacturer's web site at http://www.usa.canon.com/consumer/controller?act=ModelInfoAct&tabact=DownloadDetailTabAct&fcategoryid=346&modelid=15431

I don't think the P23-DH has a calendar/clock mode. I have found the instructions for setting date and time for the P23-DH V. If your calculator does not have [Calendar/Clock], [Time Set], and [AM/PM] keys, you cannot set the date and time.

To set date:
1. Press the [Calendar/Clock] key once
2. Press and hold the [Time Set] key for three seconds
3. Enter the date in MMDDYYYY format
4. Press the [Time Set] key
5. Press the [C/CE] key

To set time:
1. Press the [Calendar/Clock] key twice
2. Press and hold the [Time Set] key for three seconds
3. Enter the date in HHMM format, press [AM/PM] key if necessary
4. Press the [Time Set] key
5. Press the [C/CE] key

What I do is just base the time on quarter hour and the 24 hour clock.

Example

6:30am = 6.5

3:45pm = 15.75

every 15 min = .25

Clock in at 11:45 am and clock out at 5:15 pm
17.25-11.75=5.5