LiftMaster CB22 Instructions page 33

RPM SENSOR (OPTIONAL) 041ACOM17001
A rotational speed sensor (RPM sensor) can be optionally installed.
The sensor is attached to the motor and fastened using two screws.
The sensor enables the automatic reversing of the gate if an
obstacle is detected and should be set as sensitive as possible. The
sensor is only active during the drive's fast run. It is switched off for
the soft stop (slow run). RPM sensor: Connector CN3 on the control
board
ELECTRIC LOCK (OPTIONAL) 203285 (12V)
An electric lock can be connected to the control board using the
connector CN1. An additionally available small relay control (207399)
is connected between the drive electronics and the e-lock.
Do not use any fixed copper lines. Do not lay any 230 volt
cables in parallel and do not lay any 2 cables in the same cable
trunking.
RADIO MODULE (OPTIONAL)
To operate the control board via radio remote control, a radio
module must first be installed in slots CN4/CN5. The following
modules are available: 801221 (433.92 MHz), 801429 (27.145
MHz), 207542 (315.15 MHz China)