DS2422 Maxim, DS2422 Datasheet - Page 18

• Manufacturer Part Number: DS2422
• Description: The DS2422 temperature/data logger combines the core functions of a fully featured data logger in a single chip
• Manufacturer: Maxim

ALARM STATUS
The fastest way to determine whether a programmed alarm threshold was exceeded during a mission is through
reading the Alarm Status Register. In a networked environment that contains multiple DS2422-based dataloggers
the devices that encountered an alarm can quickly be identified by means of the Conditional Search command (see
ROM Function Commands). The data and temperature alarm only occurs if enabled (see Temperature Sensor
Alarm and Serial Input Alarm). The BOR alarm is always enabled.
Alarm Status Register Bitmap
There is only read access to this register. Bits 4 to 6 have no function. They always read 1. All five alarm status bits
are cleared simultaneously when the Clear Memory function is invoked. See Memory and Control Functions for
details.
Register Details
GENERAL STATUS
The information in the general status register tells the host computer whether a mission-related command was
executed successfully. Individual status bits indicate whether the DS2422 is performing a mission, waiting for a
temperature alarm to trigger the logging of data or whether the data from the latest mission has been cleared.
General Status Register Bitmap
There is only read access to this register. Bits 0, 2, 5, 6, and 7 have no function.
TLF: Temperature Low
Alarm Flag
THF: Temperature High
Alarm Flag
DLF: Data Low Alarm Flag
DHF: Data High Alarm
Flag
BOR: Battery On Reset
Alarm
ADDR
0214h
ADDR
0215h
BIT DESCRIPTION
BOR
b7
b7
1
b6
b6
1
1
BIT(S)
b5
b5
1
0
b0
b1
b2
b3
b7
WFTA
If this bit reads 1, there was at least one temperature conversion during
a mission revealing a temperature equal to or lower than the value in
the Temperature Low Alarm Register. A forced conversion can affect
the TLF bit. This bit can also be set with the initial alarm in the SUTA =
1 mode.
If this bit reads 1, there was at least one temperature conversion during
a mission revealing a temperature equal to or higher than the value in
the Temperature High Alarm Register. A forced conversion can affect
the THF bit. This bit can also be set with the initial alarm in the SUTA =
1 mode.
If this bit reads 1, there was at least one data value read from the serial
data interface during a mission revealing a value equal to or lower than
the value in the Data Low Alarm Register. A forced conversion can
affect the DLF bit.
If this bit reads 1, there was at least one data value read from the serial
data interface during a mission revealing a value equal to or higher
than the value in the Data High Alarm Register. A forced conversion
can affect the DHF bit.
If this bit reads 1, the device has performed a power-on-reset. This
occurs when the V
when the power supply gets interrupted. The trim settings need to be
restored for proper function. Any data found in the datalog memory
should be disregarded.
b4
b4
1
MEMCLR
DHF
18 of 49
b3
b3
BAT
DLF
b2
b2
0
power source gets first connected at assembly or
THF
MIP
DEFINITION
b1
b1
TLF
b0
b0
0