The 3 wire probe can be hooked up to the EDC or the D180's D37, while the 2 wire probe can only be connected to the D180's D37. Assuming you're configuring the D180 as the DSAB master, hook one of the probes up to it, in the configuration that you prefer. Then make sure that only that configuration (either the EFIS>SETUP>OAT or the EMS>SETUP>GP Input) is set to have an OAT probe hooked up. The D100 would then be set to OAT: N under that unit's OAT setup menu. Do a DSAB config and you're good to go.