Sigma C4 - page 44

44 C4 Manual Rev 7.5.2
5.4 Compressor Control (mechanically refrigerated unit control only)
The compressor of a system employing mechanical refrigeration can be manually
toggled at any time during local mode controlling operation by pressing the
<REFER> button. The REFER LED on the front panel indicates the state of the
refrigeration compressor control port. The port is shut off when controlling action
is stopped by pressing the <START/STOP> button and restarted if
<START/STOP> is pressed again before the rotary switch is moved to a mode
other than Local or Off.
The controller can be configured to not respond to front panel <REFER>
(compressor) ON/OFF commands. See SETUP mode, Section 8 - setup parameter
F13.