I've got an issue with the low-power mode on the DT80. It's probably due to my misunderstanding of how it works, so I'd appreciate some help!

I have a very simple setup with a DT80 connected to a sensor on a digital input and increment a counter each time the sensor is activated. DT80 is externally-powered (through the screw-terminal connector as recommended in the manual) and also has the battery link in.

It is my understanding that in this setup, with P15=0 (as is default), DT80 should not go into sleep mode (as long as the external power is on). However, it appears to go to 'sleep' anyway.

The unit is locked away in an inaccessible area, so the this problem went unnoticed until an attempt was made to retrieve the data and none was found on the logger. To avoid this, I have had to set P15=2, though this is not an ideal solution as it means that when the external power is switched off (as it is at night), the battery will discharge more rapidly than necessary.

Any thoughts on this would be appreciated.

Many thanks,
Simon

Good afternoon Simon,

Could you please give us some more detail on what it is you are trying to do? If I had to guess, it looks like you have a flow meter or a rain gauge and are trying to count the pulses.

When counting things like pulses it is always best to connect the input to a high speed counter. (Even if it is a slow speed pulse) The High Speed counters will count even when the logger is in sleep mode.

The digital inputs, on the other hand, will not count when the logger is in sleep mode. Sleep mode P15=0 will still allow the dataTaker to sleep when powered from a plug pack. The dataTaker will wake up when a schedule is due, on communication etc.

Cheers,
Roger

Hi.

I'm using the dataTaker to log items coming off the end of a packaging line. The sensor is a basic through-beam device. Are you saying that the DT80 will go into sleep mode when externally powered and P15=0?

This doesn't seem to match with the manual (p157):

By default, the DT80 will only go into sleep mode if:

• it is battery powered (ie. external power is not connected), and
• the Ethernet port is not connected, and
• the USB port is not connected

I would read this as saying that the DT80 will not sleep when the external power is connected. Are there any disadvantages of using the high-speed counter? If not, then this sounds like the best solution!

Many thanks,
Simon

Might seem an obvious point, but do you actually know it went to sleep? How? With P15=2 is all OK?

If all is working with P15=2 I then guess that you don't have a time based schedule trigger for the counter logging. The logger is going to sleep (no time scheduled logging) because external power is failing or being removed (power pack pulled out for someones radio etc).

Check the event log as well, it will show if external power is being cycled.

Have fun!

I think it went to sleep because I was able to get access to the DT80 and saw that the display was blank. Pressing a button on the front brought the display back on (and the back light too), but after a while (several seconds) the display switched off again.

So you're saying that with P15=0, it must be the external power supply failing or being removed for the DT80 to go to sleep? This was my first thought, but having spoken to the electricians who installed it, it's being powered from the packaging line (a protected power supply) and any failure of this supply would be picked-up elsewhere.

When I'm next able to access the DT80 I'll get the event log off it and have a look at that. (Thanks for the suggestion, hadn't thought of that.)

You're right - there's no time-based schedule trigger for the counter logging. It seems to be operating fine now with P15=2, although this means that the battery will be discharging every night when the power supply is switched off.

I had another DT80 elsewhere that wasn't showing the same issues, so I went to check on it to see what was different. It turns out that there's some problem with the battery in that unit (display shows 'NC'). It seems that this means the unit will never go to sleep as it's always running off the external power source (when it's present). I suppose this means that removing the battery from the first unit is a potential solution - there will never be a need to log when external power is absent.

Thanks for your input (Roger and SuperMono) - it's greatly appreciated!

Simon