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In my application, I want to display for how long a procedure will be active. There will be a trigger enable line that can turn on the timer to keep track of number of minutes / hours.
When the users stop that activity, I want the counter to keep displaying previous number of minutes / hours and start counting from that previous time onwards to accumulate total number of hours used.
With memory, the counter should retain previous number of hours usage if the unit is turned off.
There will be a RESET switch to zero the display and erase the time stored.
Would 701PR-112 / TR114B0A work in this application?
how does it count time? would it hold time when enable line goes low? would it save time in memory and count up from previous number in case of power loss? how to reset count hours?
As I understand your application, you are seeking a two-line display:
Line 1: total run time
Line 2: time current cycle
Other specifications include:
retentive memory to remember total system time across power outage
ability to reset time back to zero
unclear if the “cycle active” line is pulsed or constantly on for the cycle duration
opportunities for future expansion
The devices you mentioned do not have this level of sophistication. They are more like an hour meter you might find on a payloader or other piece of industrial equipment.
Perhaps you are looking for a Programmable Logic Controller (PLC) with an integral or external Human Machine Interface (HMI). Another alternative is to construct your own device using a microcontroller with an LCD display.
Based on this question, I suspect you would be time and money ahead using a PLC.
Please respond by telling us a more of your project details and your level of experience. This may help to select the optimal solution.
In hours and tenths of an hour, up to 99,999.9 hours.
Yes
Yes, with 25 year data retention
With a switch connected to the reset connection and V+.
See the user manual for details:
A big problem you may have is the relatively low accuracy of its timekeeping. The spec is +/-0.1% which is about +/-8.75 hours per year. That is an acceptable accuracy when used for measuring service intervals of industrial equipment but may not be OK for your application.
Most excellent clocks are accurate to +/-0.0002% (2 ppm) which is about +/-1 minute per year. The least expensive digital clocks/watches are usually accurate to +/-0.002% (20 ppm) which is about 1 minute per month.
Thank you so much for your response. Much appreciated!
Although displaying time for the current cycle might be a good idea in this application, I was just planning to show the total run time so far with hours keep accumulating until Reset is pressed externally.
The external timer should be able to retain total elapsed time in non-volatile memory and add to it when enabled again. It should have the ability to reset to zero when triggered by the user. Enable line will be constant high while in usage, and not pulsed.
While I can design this with a micro and a separate LCD, I would prefer to use a dedicated timer such as 701PR-112 / TR114B0A, if possible?
Thank you so much for your response. Much appreciated!
For this application, 60mS of accuracy in an hour would be acceptable as long as it meets the design requirements and relatively simple to interface with my device.
As in my device, I’ve an edge triggered interrupt for micro that activates the device.
I plan to use the same interrupt to trigger the enable line for the timer to keep track of active usage.
Interrupt line goes high when active and low when deactivated.
Microcontroller with its own 32.768 clock oscillator.
Offload the time functionality to a totalizer such at the devices you mentioned
Offload the time functionality
IMO, the selection process is heavily dependent on end use and total number of devices to be manufactures. The microcontroller is wonderful for high volumes. Purpose build timers are very easy to use. On the other hand, the PLC shines for one-off applications where technicians may be called upon to maintain or repair the device.
Please let us know if we can assist in the future.
