Phototransistor transimpedance circuit

[adinogcas]

Just quick question...

What is the output of this circuit? (suppose Vdac=0=GND)
Ip=Photo current

will it be Vo= -Ip * R
or V0=Ip*R?

And why? Because someone told me it should be -Ip*R not Ip*R. And most of transimpedance circuit use in different configuration.

I am getting confused here. Please help!

 

[mneary]

The DAC input on the + pin makes it impossible to calculate.

The net current in/out of the op amp pin 2 is theoretically 0. This should help.