The PD Pro accepts up to two compatible snow/ice sensors.
The SCA-DUAL / PD Pro is designed for up to two compatible snow/ice sensors. Do not add more sensors to its inputs.
The manual lists Snow Owl aerial, GIT-1 gutter, and SIT-6E pavement sensors, with recommended combinations for the installation. Choose the combination from the manufacturer’s table for the intended application; compatibility does not mean every arbitrary combination is recommended.
The optional high-temperature sensor is a separate accessory and function. Its presence does not increase the supported snow/ice-sensor count.
For comparison, the linked APS-3C manual describes support for up to six compatible sensors. That is a different controller and does not change the PD Pro limit.
Sources
- Manufacturer instructions (publication 3508), PDF pp. 6–7.
- Manufacturer instructions (publication 980), PDF pp. 3–4.