Sum hours ran then reset

[VSeaver]

Hello,

This may be done someway different, but I am looking for either a formula or VBA to add hours ran on a machine. I have a calendar on a spreadsheet. I will input the hours each day the machine ran. I want to add these hours in a different cell. Once we do a PM on the machine, I want to reset this number and start over the hour count.

Thanks
Vince

 

[VSeaver]

So....I made some modifications to see if that can help with my problem. I still have the same calendar. In separate cells I will input the date and shift the PM was done on. What I want to accomplish is to sum hours based on these two cells. So lets say I put 4/2/18 in this cell A1 and put "2nd" in cell A2, I want start adding hours the next day. If I put 1st in, I want to start adding hours that day. Not sure if that makes any more sense or not.

Thanks