To understand the Dip switch it first needs to be understood the concept of the PPS net.
The GNSS module guide goes into detail about the Net and the pins which can be found here
but it could be simpler to look at the below diagram.
As the above diagrams suggests you have items running in to the net and out of the net, GNSS in and PPS in are not compatable at the same time so it follows that one must be off.
As our units ship with GNSS In configured we have to turn off PPS IN using the Dip Switch.
For that we flip switch number 4 to off.
This means that The GNSS is the driving input of the unit. If you want to have PPS enter the PPS Net and not the GNSS you will turn switch 4 back on and then switch off number 2 like the below: