Hanna Instruments HI 504901 - Manual (Page 11)

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Note The “Query Delay” time value fixes the maximum delay be-
tween an alarm occurrence in a device and the related alarm
SMS sending by the interface.
SMS can be submitted by the HI504901 supervisor only if
the SMS sending feature is enabled through an external switch
(see further on for details); if the SMS sending is disabled,
then no message will be sent upon alarm or fault condition
on connected devices.
Note To make the HI504901 queries the connected devices and
sends SMS’s, it is necessary to configure the interface, other-
wise no polling procedure can take place and no alarm no-
tification will be given by the interface. HI504901 can not
automatically detect which instruments are connected to the
interface; moreover, the user must select for which type of
alarms he wants to receive warning SMS’s.
While in idle state, the SMS sending feature can be disabled
or enabled by the user at any time, by simply closing (or
opening) the proper external switch. If no error indication is
already active, then the red and green LED’s (# 5 and #6
on page 9) keep indication about the SMS sending enable/
disable status:
Note Sometimes the updating of LED indication about SMS send-
ing status can take a few seconds after changing the external
switch status by the user. This happens if the interface is busy
while performing procedures as polling devices, SMS send-
ing, incoming call processing, etc.
While in idle state, HI504901 can serve also incoming re-
quest for configuration or PC communication session
activation (both local and remote), but remote sessions (both
configuration and PC communication) can take place only if
no cellular errors are active on the interface.
External Switch LED Status Meaning
Open SMS enable (green) ON SMS sending enabled
SMS disable (red) OFF
Close SMS enable (green) OFF SMS sending disabled
SMS disable (red) ON
Also the digital output status LED is updated with the current
status of the digital output contact. The digital output contact
status can be changed by the user only by sending the proper
SMS to the interface. The below table shows the digital output
LED indication depending on the digital output status:
Note The status of the digital output contact is saved in HI504901
internal memory, so that the digital output is set to the correct
value in case of a reset or after a start-up of the interface.
During polling procedure all devices connected to the inter-
face through RS232, RS485 serial ports and digital input port
(if correctly configured, see “Interface Configuration” sec-
tion) are periodically queried to acquire their current status,
measurement values and active alarms. The delay between a
query operation and the following one is user selectable, and
can vary from 1 to 10 minutes (see “Query Delay” field and
“Interface Configuration” section).
If many devices are connected to the RS485 link and the
cellular phone interface can not interrogate all the devices
within the selected delay time, then the actual interval be-
comes longer than the set value.
When polling devices procedure is completed, if some alarm
is active on the device connected to an RS232 port channel,
the corresponding LED (#1 and #2 on page 9) will light up;
besides, the RS485 serial port LED (#3 on page 9) lights up
if an alarm is active at least in one of the instruments con-
nected to the RS485 port (up to 32 devices can be connected
on the same RS485 port); the digital input port LED turns on
or off depending on the user-selected logic for closed con-
tact (if control of digital input port was user-enabled during
last interface configuration).
Moreover, if an active alarm found in a device connected to
the HI504901 matches with one of those selected by the
user during last interface configuration, or if the digital input
status matches with the condition selected for triggering an
alarm message, then one (or more) SMS(s) are immediately
submitted by the HI504901 to the set cellular phone
number(s) (see SMS delivery” section).
LED Status Meaning
Digital Output OFF Dig.output contact open
(yellow) ON Dig.output contact closed