Detcon RXT-300 - Manual (Page 37)

RXT-300 SmartWireless™
RXT-300 Wireless IM Rev. 2.0 Page 31 of 41
5.3.3 Register – 4-20mA Reading
There are two 4-20mA inputs and their current value is stored in the 4-20mA A and B registers. The value of
these register will range between 0 to 2048 with 0 being 0mA and 2048 being 20.48mA. Therefore a 4mA
input will read 400 and a 20mA input will read 2000. Any currents above 20.48mA will remain at 2048 since
this is the maximum value for this register.
5.3.4 Register – Battery Info
If a Detcon battery pack is connected to the RXT-300 transceiver, there are multiple registers associated with
information about that battery. The RXT-300 utilizes the I2C interface to read battery status and only one
Detcon battery pack can be read per RXT-300.
The controller can determine if a battery is present by reading the Status Register (register 72). There are three
bits in this sixteen bit register pertaining to the battery, Battery Attached – bit 15 (lowest bit is 0), Battery
Alarm – bit 7 and Battery Fault – bit 6. The Battery Alarm and Fault bits default to a value of 0. Battery
Attached will be set once a read of the battery over the I2C interface was successful or it is set by the user in
the configuration. Battery Alarm will be set if the RXT-300 determines the remaining life is below the
threshold configured by the user. Battery Fault will be set if a battery was Attached (or detected) but the last
read failed. Battery Fault is re-evaluated upon every read of the battery which is set to approximately every 60
seconds.
Once the battery has been detected and has no fault, the controller can read the battery life (registers 7 and 8)
and the voltage (register 9). The battery adjusts the battery life values based upon the average current usage.
If the current usage varies widely over time it will take some time to re-adjust the battery life readings. For
instance, an Alarm Station with no alarms will consume a very small amount of battery but when Alarms are
active this will jump to a much higher level of usage. So in this case battery life may go from several weeks
down to several hours.
The battery life is presented in two forms, life remaining in percentage (register 7) and life remaining in
minutes (register 8). The battery Life remaining is percentage is a value between 0 and 100 and battery life in
minutes is an unsigned value between 0 and 65535. Both readings are generally necessary to provide
appropriate feedback to the user. Life in minutes is the best for determining when to change the battery. The
RXT-300 configuration is set to days / hours /minutes so the user could set it to 1 day to allow time to replace
the battery.
Since 65535 is the maximum value for life remaining in minutes, this represents a maximum of 45.5 days.
The battery life for an application can be much greater than this value and will remain at a reading of 65535
until it drops below this. Life in percentage was added for this reason. Percentage will track starting at 100
percent and drop down as battery life decreases.
5.3.5 Register – uC Firmware Version
This is set to a value based upon the version of firmware programmed into the RXT-300 microcontroller. It is
stored as two byte value representing the major and minor revision numbers. So a 0119h (281 decimal)
represents a major version of 01 and minor version of 19. As software is updated this will be incremented
appropriately.
5.3.6 Register – Radio Firmware Version and Build
This is set to a value based upon the version of firmware programmed into the RXT-300 radio microcontroller.
It is stored as three byte value representing the major / minor in register 48 and build revision in register 49.
So a value in register 48 of 0204h in the (516 decimal) represents a major version of 02 and minor version of
04 and a 0009h in register 49 represents build version of 9. As software is updated this will be incremented
appropriately.