Specifications

Section 2: System Description
2-9
TERMINAL
The terminal port on the Alto 818 is an RS-232C serial data port that is used to connect the ACU
to a local terminal or printer. The maximum cable length from the ACU to a terminal port device
is 25 feet (7.6 m). In stand-alone mode, control of the Alto 818 is usually through this port. For
terminal interface wiring details, see Section 4.7.
ANNUNCIATOR
The annunciator connector is used to connect an SE 778-A Annunciator/Control module to the
Alto 818 to provide a number of monitor inputs. See Section 2.4 for a description of the SE 778-
A. For interface wiring details, see Section 4.9.
RS-485
The RS-485 connector is the S-Net connector, the serial link to the DigiReader and VIP2s on the
network. For interface wiring details, see Section 4.3.
SENSORS
Sensor ports 1 through 8 provide connections for analog proximity sensors or SE 774-A Multiple
Switch Monitors (MSMs). Each MSM can support one proximity sensor and up to four monitor
points. With a complete complement of eight MSMs, the Alto 818 can support of 8 sensors and
32 monitor points. See Section 2.5 for a description of the MSM.