7-1
Chapter 7
4253 Input/Output module 16/8
& 4953 I/O Status Display module
Description
The 4253 I/O module provides 16 supervised inputs and 8 relay
outputs.
The 4953 Status Display module fits onto the 4253 I/O module and
provides LED indications showing the states of all the inputs and
outputs. There are no external connections to the 4953 module.
Supervised inputs
Each input is monitored for change of state and also for open/short
circuit (tamper). The polarity of eight of the inputs can be selected
using eight jumpers on the module circuit board (JU13 to JU20). The
other eight inputs are fixed to “normally closed” (input is active when
switch contacts are open).
Relay outputs
When an output is activated, its relay is energised. The 4253 I/O
module has eight single pole relay outputs with just two connections
for each - O# and C#. The polarity of each output (normally open or
normally closed) is selected using eight jumpers on the module circuit
board (JU1 to JU8).
Each pair of outputs - O1/O2, O3/O4, O5/O6 and O7/O8 - can be
linked so both relays are energised together when the first output of
the pair is activated. Jumpers JU9 to JU12 set this function.
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