Hey DC
For you and everyone else
VCC - refers to the IC power supply input pin - this is the positive voltage pin.
https://en.wikipedia.org/wiki/IC_power-supply_pinTypical supply pin labeling
VCC = VDD = V+ = VS+ = Positive supply voltage = in this case 5V+
The Negative supply voltage which is often Ground or V0 can be also labelled
VEE = VSS = V− = VS− = Negative supply voltage, in this case V0 or GND
Confusing and possibly unnecessary - yes but that's the way people have done things
Now with a bit of logic
The Piranha IR signal input is an input. So you connect an Output into an input, hence.
TXO: Serial output from OpenLog - goes INTO the Ir Signal input
Now with a bit of deduction there is only one pin left on the Piranha (LED-) since LED+ is 5V+ also. Therefore....
LED- goes into RXI: Serial input into OpenLog
This is not initially clear until you realise that LED- is controlling the indicator LEDs and thus has to be an output (controller outputs signal to control LED flashing).
On the OpenLog board the extra pins are:
BLK - well they tell you this is an additional GND pin - so you can connect GND to BLK if you wanted. But just ignore it
GRN is a reset pin the OpenLog controller - no need to do this so you can leave it alone also.
NOW one word - CHINA
If you have a cheap OpenLog unit from China it may be running the BlackBox firmware which I do not know if it will work - What does work is the OpenLog original firmware as on an Original unit if bought from say SparkFun in the US. It is simple to reload new firmware. The OpenLog pages on SparkFun will tell you how.
Now second word - Updates
Which each Asp update more has been added to the OpenLog function. In the latest Asp release plugging openlog into piranha ONLY allows changing of the IR battle parameters. All parameters can be edited if plugging direct into the Asp2 board and editing the aspsetup.txt file
Cheers
KG