Studer OnAir 1500 Operating Instructions Manual page 311

OnAir Digital Mixing Consoles
C1 Configuration
6-92 Configuration
Console 1 is an OnAir 3000, its identifier is FixFrame in our example.
Step 1 GPInputFunction 11 is set to UserLED and Funct 5; this way, with its
input signal, the LED of user key no. 5 can be turned on or off (of course this
needn't be GPInputFunction 11; just select the first free function available).
After scrolling down, the parameters Time are set to 0 ms, Triggered Edge
to both, and Activate to On.
Step 2
GPInputFunction 17 is set to UserKey and Funct 5, which means that user
key no. 5 may also be operated remotely instead of manually. The control
Source is the output of AND 4. Since its Action parameter is set to set only
low, it can only be turned off remotely. After scrolling down, the parameters
Time are set to 0 ms, Triggered Edge to rising Edge, and Activate to On.
SW V6.0 Document generated: 06.08.14