Rainbow Electronics DS2422 - Manual (Page 47)

DS2422
47 of 48
STEP 2
During the setup, the device needs to learn the following information:
§
Time and Date
§ Sample Rate
§ Alarm Thresholds
§ Alarm Controls (Response to Conditional Search)
§
General Mission Parameters (e. g., channels to log and logging format, rollover, start mode)
§
Mission Start Delay
The following data will setup the DS2422 for a mission that logs temperature using 8-bit format. Such a mission
could last up to 56 days until the 8192-byte datalog memory is full.
ADDRESS DATA EXAMPLE VALUES FUNCTION
0200h 00h
0201h 30h 15:30:00 hours Time
0202h 15h
0203h 01h
0204h 04h 1 st of April in 2002 Date
0205h 02h
0206h 0Ah
0207h 00h
Every 10 minutes (EHSS = 0) Sample rate
0208h 52h 0°C low Temperature Alarm
0209h 66h 10°C high Threshold
020Ah 00h External Data Alarm
020Bh FFh
(Don’t care)
Threshold
020Ch FFh
020Dh FFh
020Eh FFh
020Fh FFh
(Don’t care) Clock through read-only registers
0210h 02h Enable high alarm Temp. Alarm Control
0211h FCh Disabled Data Alarm Control
0212h 01h On (enabled), EHSS = 0 (low sample rate)
RTC Oscillator Control, sample
rate selection
0213h C1h Normal start; no rollover; 8-bit temp. log General Mission Control
0214h FFh Clock through
0215h FFh
(Don’t care)
read-only registers
0216h 5Ah
0217h 00h 90 minutes Mission Start Delay
0218h 00h
With only a single DS2422 connected to the bus master, the communication of step 2 looks like this:
MASTER MODE DATA (LSB FIRST) COMMENTS
TX (Reset) Reset pulse
RX (Presence) Presence pulse
TX CCh Issue “skip ROM” command
TX 0Fh Issue “write scratchpad” command
TX 00h TA1, beginning offset=00h
TX 02h TA2, address=0200h
TX <25 data bytes> Write 25 bytes of data to scratchpad