Hallo everybody. I would like to open the gate manually but i don't know how to configure the plugin for that.
Does anybody has a tip for me?
 
Thanks, Tomas

Slight confusion here, what do you mean manually, most Gate's are controlled by signal level threshold. 

I suppose you could automate the bypass or power.

PC4K S Type Expander/Gate Video
 
Not sure which exact gate in cakewalk you are referring to.
These basic functions translate to many Gates.

If you mean Sonitus:Gate (Cakewalk's gate, included in SONAR), slide the leftmost slider up from the bottom (threshold) and the next slider on the right down (how many dB gating is done).

Could be this one.

scook
Could be this one.

Exactly this plugin i mean. In the online discription is written the following

Manual Trigger-This is a two-state control that allows you to manually toggle the gate. An anticipated use would be to assign a MIDI Note ON/OFF (via remote control) to the gate trigger to manually affect a "stutter" result in the mix. When the trigger is on, the gate is fully closed, meaning no signal passes through at all, despite threshold settings. 

what I did not find is how to map the midi command.

Tomas with the plug in the FX bin, if you expand the control lane of the track you will see a control lane called Volume.

If you click on the down arrow next to the word volume you can reassign the lane to a new value.
Select the Compressor/gate option
Last but one option is Manual trigger.
Now by setting the control lane value high or low you can trigger the gate on and off.