Microtel Series 500 - Manual (Page 23)

16
III.F.2. 8 Channel Digital Input Card
The 8 Channel Digital Input card is designed to accept up to eight channels of dry (un-
powered), normally open or normally closed signal lines. The system provides a small
sampling current (<10mA) to determine if the contact is open or closed. Wires from
normally open or normally closed switches may be routed through the conduit port at
the lower right side of the system. Connect each wire pair to its appropriate channel
input terminal and one of the two common ground terminals provided on the digital Input
circuit card. Shielded, twisted pair, #20 or #22 gauge wire is recommended. If shielded
cable is used, ground the shield at the sensor and leave the shield floating
(disconnected) at the Dialer system. Refer to the Electrical Installation Diagram located
in the appendix for details on wire routing procedures.
Each input channel must be configured to be either normally open or normally closed.
A channel is normally open if the “no fault” or “normal” condition is that condition which
consists of an open circuit on the channel’s wire pair. The normally open or normally
closed state of each channel may be programmed as outlined in the Section entitled,
Programming the System.
Any unused channels should be programmed as normally open, and left unconnected to
reduce overall system current consumption. Setting the Mode of an unused Channel to
IGNORE speeds up the System operation. When the option card is installed it must be
“initialized” to inform the system of its presence. During initialization, each digital input
channel is automatically programmed by the system for various operation data values
(default values). The default for the channel’s mode is set to STATUS, meaning its
alarm condition is reported, but it will not cause calls to be originated.
III.F.3. 4 Channel Analog Input Card
The Analog Input option card will accept four, 4 to 20mA current loop signals. The
current loop signal must be externally powered. The System will monitor the current
and continuously compare the reading against high and low set-points. The results of
that comparison will determine whether or not the dialer places a telephone call
because of an alarm condition. Additionally, the High, Low, and Normal indications for
each channel may be displayed on the system LCD panel, showing the monitored
status of each channel. Two wire, shielded cable may be connected to the terminal
strip provided on the analog option card, for each channel. Shielded, twisted pair, #20
or #22 gauge wire is recommended. If shielded cable is used, ground the shield at the
sensor and leave the shield floating (disconnected) at the MCS 500 system. Refer to
the Electrical Installation Diagram located in the appendix for details on wire routing
procedures.
During card initialization, each analog input channel is automatically programmed by the
system for various operation data values (default values). The default for the channel’s
mode is set to IGNORE, meaning it is completely disregarded by the system. This is
done to assure that the system spends no wasted time on invalid or unused channels.