What is the maximum voltage I can input to the extra dry contacts on the securityProbe8-X20?

AKCPsecurityProbe Series, Support

What is the maximum voltage I can put on sensorProbe8-X20 dry contact inputs? You can input up to 30 Volts DC to the extra dry contacts, as long as you have them configured as opto isolated. See Question #1 in the “How Do I” section of this knowledge base for instructions on how to set the dry contacts to opto isolated mode

AKCPWhat is the maximum voltage I can input to the extra dry contacts on the securityProbe8-X20?