Power failure – Hanna Instruments HI 504903 User Manual
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POWER FAILURE
The power failure status is the working mode of HI504903
when the mains power supply fails and the interface works
using the internal backup battery.
In this situation the green “SMS enable” and red “SMS dis-
able” LEDs are in the following conditions:
LED
Status
Meaning
SMS enable (green)
blinking
SMS sending enabled
SMS disable (red)
OFF
SMS enable (green)
OFF
SMS sending disabled
SMS disable (red)
blinking
All other LEDs (excluding the digital output LED when the
digital output contact is closed) are turned off.
If the SMS sending is user enabled, then alarm SMS related
to power failure event will be sent by HI504903 to the pro-
grammed number(s) (see “SMS delivery” section).
After that, if
1. sending of maximum number of repeated messages is
reached without user confirmation, or
2. HI504903 receives a phone call from one of the pro-
grammed number(s) to confirm alarm SMS reception, or
3. SMS sending is disabled through external switch,
then HI504903 turns off the cellular phone engine to pre-
vent internal backup battery consumption.
Note
If SMS sending was disabled before power supply failure event,
then cellular phone is immediately turned off and no alarm
will be issued by interface.
While in power failure status HI504903 does not perform
device polling procedure, so that new alarms on instruments
connected to the interface can not be notified.
Also interface configuration and PC communications (both lo-
cal & remote) are not allowed until mains supply comes back.
When the mains power supply comes back, the cellular phone
turns on and cellular initialization procedure takes place (it
keeps about 30 seconds). As in start-up procedure, during
cellular phone initialization the red LED for SMS disable turns
on while the green LED (SMS enable) turns off. When cellular
phone is ready, HI504903 sends the SMS “Power is OK now!”
to the programmed number(s), if SMS sending is enabled.
everything is works like a direct point-to-point connection (if the
delay issues are excluded). No need to change baud rate value
on PC side as modem buffers handle automatically the baud
rate difference (remember that the baud rate must be kept at
9600 bps in remote communication on PC).
Local PC connection closure
The application software can close a local PC connection pull-
ing down the DTR line of the serial port at any moment.
Remote PC connection closure
The application software can close a remote PC connection
hanging up the data call sending to the modem “+++” and
then, after “OK” reception, “ATH
moment.
An automatic disconnection on HI504903 side takes place if
no character is received in 8 minutes.
LEDs STATUS DURING PC COMMUNICATION SESSION
Following is a table with all possible status of HI504903 LEDs
during a PC communication session:
LED
Status
Meaning
RS485 channel (red)
Digital input (red)
SMS enable (green)
SMS enable (red)
Digital output (yellow)
Cell signal quality
(2 green LEDs)
Cell status (yellow)
OFF
Not yet channel selection made by
remote PC
Blinking
Communication session in progress
between remote PC and one or more
HI142 dataloggers on RS485 channel
OFF
--- (no meaning)
OFF
--- (no meaning)
ON
--- (no meaning)
ON / OFF
Indication about digital output
previous status (ON if contact closed,
OFF if contact open)
both OFF, or
Indication about last cellular signal
ON + OFF, or
strength before PC communication
both ON
session beginning
ON / OFF / blinking Cellular phone real time operating
status (fast blinking if remote
communication is taking place)