Teledyne 3350 - Microprocessor based control room monitor for personnel safety - Manual (Page 23)

3-7
Alarm Oxygen Monitor Installation 3
Teledyne Analytical Instruments
Each status output is followed by a carriage return and line feed.
The RS-232 protocol allows some flexibility in its implementation.
Table 3-2 lists certain RS-232 values that are required by the 3350 imple-
mentation.
Table 3-2: Required RS-232 Options
Parameter Setting
Baud 2400
Byte 8 bits
Parity none
Stop Bits 1
Message Interval 2 seconds
Alarm Relays must not be connected to any voltage
source greater than 130VAC. Minimum recommended
wire is 16 AWG with 300 VAC insulation
3.5.5 Alarm Relays
The three alarm-circuit connectors are screw terminals for making
connections to internal alarm relay contacts. There is one set of contacts for
each of 3 different types of alarm. Alarm 1 (CAUTION), Alarm 2 (DAN-
GER), and Cell Fail. Contacts are Form C, with normally open and nor-
mally closed contact connections capable of switching up to 3 ampere at 130
VAC into a resistive load (3A for 30 VDC) maximum.
The alarm relay circuits are designed for failsafe operation, meaning the
relays are energized during normal operation. If power fails the relays de-
energize (alarms activated). Alarms are also available factory configured for
non-failsafe operation which would extend the life of the battery standby
power if applicable.
The contact connections are indicated diagrammatically on the rear
panel as Normally Closed, Common, and Normally Open. Figure 3-5
explains how these act in failsafe operation.
Figure 3-5: Contact ID for FAILSAFE Relay Operation