Precision Digital PD138 - Manual (Page 30)

PD138 Minimux
®
II Temp & Process Scanner Instruction Manual
30
Sequence F2A
The main feature of Sequence F2A is its ability to indicate which alarms
occurred first (on a scan cycle, see page 26).
The PD138 is scanning all the
selected inputs and is currently at
channel 2, as indicated by a green
LED. After the Minimux
®
II has dwelled
on channel 3 for the appropriate
settling time, it poles channel 3’s
alarm-in line and finds it to be in
alarm. The LED starts flashing
yellow (red and green), the horn
sounds and the alarm relay
transfers.
Channel 5 is also found to be in
alarm and the LED flashes
because it was detected during the
same scan cycle that the first
alarm was detected. Channel 4 is found to be in alarm
and is indicated by a steady LED
because it was found after a
complete scan of all inputs after
the first alarm was detected.
1
2
4 3