Protocol of WM918 Electronic Weather Sataion

Revision: 8/18/1999

Blank entries indicate undefined or unknown data.

This information may be freely distributed.
									
Byte	Nibble	Bit(s)	Datum	Description 'part' of lo<format<hi unit @ resoltion
									
8F. 0	HH	all	Group	8F ----------------------------------------
8F. 1	DD	all	Time	Second 0<ab<59 @ 1
8F. 2	DD	all	Time	Minute 0<ab<59 @ 1
8F. 3	DD	all	Time	Hour   0<ab<23 @ 1
8F. 4	DD	all	Time	Day    1<ab<31 @ 1
8F. 5	Bx	0	Time	Format: 0=12 Hour,  1=24 Hour	
8F. 5	Bx	1	Time	Format: 0=Day-Month, 1=Month-Day	
8F. 5	Bx	2,3
8F. 5	xH	all	Time	Month: 1=Jan, 2=Feb, ... B=Nov, C=Dec
8F. 6	DD	all	Time	Alarm: Minute
8F. 7	DD	all	Time	Alarm: Hour
8F. 8	DD	all	Humid	Indoor:    10<ab<97 % @ 1
8F. 9	DD	all	Humid	Indoor Hi: <ab> %
8F.10	DD	all	Humid	Indoor Hi: Minute
8F.11	DD	all	Humid	Indoor Hi: Hour
8F.12	DD	all	Humid	Indoor Hi: Day
8F.13	Dx	all	Humid	Indoor Lo: 'b' <ab> %
8F.13	xH	all	Humid	Indoor Hi: Month
8F.14	Dx	all	Humid	Indoor Lo: Minute 'b' of <ab>	
8F.14	xD	all	Humid	Indoor Lo: 'a' of <ab> %	
8F.15	Dx	all	Humid	Indoor Lo: Hour   'b' of <ab>	
8F.15	xD	all	Humid	Indoor Lo: Minute 'a' of <ab>
8F.16	Dx	all	Humid	Indoor Lo: Day    'b' of <ab>
8F.16	xD	all	Humid	Indoor Lo: Hour   'a' of <ab>
8F.17	Hx	all	Humid	Indoor Lo: Month
8F.17	xD	all	Humid	Indoor Lo: Day    'a' of <ab>
8F.18	DD	all	Humid	Indoor Alarm Hi: <ab> %
8F.19	DD	all	Humid	Indoor Alarm Lo: <ab> %
8F.20	DD	all	Humid	Outdoor:    10<ab<97 % @ 1
8F.21	DD	all	Humid	Outdoor Hi: <ab> %
8F.22	DD	all	Humid	Outdoor Hi: Minute
8F.23	DD	all	Humid	Outdoor Hi: Hour
8F.24	DD	all	Humid	Outdoor Hi: Day
8F.25	Dx	all	Humid	Outdoor Lo: 'b' of <ab> %
8F.25	xH	all	Humid	Outdoor Hi: Month
8F.26	Dx	all	Humid	Outdoor Lo: Minute 'b' of <ab>
8F.26	xD	all	Humid	Outdoor Lo: 'a' of <ab> %
8F.27	Dx	all	Humid	Outdoor Lo: Hour   'b' of <ab>
8F.27	xD	all	Humid	Outdoor Lo: Minute 'a' of <ab>
8F.28	Dx	all	Humid	Outdoor Lo: Day    'b' of <ab>
8F.28	xD	all	Humid	Outdoor Lo: Hour   'a' of <ab>
8F.29	Hx	all	Humid	Outdoor Lo: Month
8F.29	xD	all	Humid	Outdoor Lo: Day    'a' of <ab>
8F.30	DD	all	Humid	Outdoor Alarm Hi: <ab> %
8F.31	DD	all	Humid	Outdoor Alarm Lo: <ab> %
8F.32	Bx	0	Humid	Outdoor: O.R. (out of range) = 1
8F.32	Bx	1
8F.32	Bx	2	Humid	Indoor Hi: O.R. = 1
8F.32	Bx	3	Humid	Indoor: O.R. = 1
8F.32	xB	0-2
8F.32	xB	3	Humid	Outdoor Hi: O.R. = 1
8F.33	Bx	0,1	Humid	Humidity Outdoors Alarm Set when both bits = 1
8F.33	Bx	2,3	Humid	Humidity Indoors Alarm Set when both bits = 1
8F.33	xB	0-2
8F.33	xB	3	Time	Alarm Set = 1
8F.34	HH	all	Cksum	Unsigned sum of first 34 bytes


9F. 0	HH	all	Group	9F ----------------------------------------
9F. 1	DD	all	Temp	Indoor: 'bc' of 0<ab.c<50 degrees C @ 0.1
9F. 2	Dx	all	Temp	Indoor Hi: 'c' of <ab.c> C
9F. 2	xB	0-2	Temp	Indoor: 'a' of <ab.c> C
9F. 2	xB	3	Temp	Indoor: Sign 0=+, 1=-
9F. 3	BD	0-2,all	Temp	Indoor Hi: 'ab' of <ab.c> C
9F. 3	Bx	3	Temp	Indoor Hi: Sign 0=+, 1=-
9F. 4	DD	all	Temp	Indoor Hi: Minute
9F. 5	DD	all	Temp	Indoor Hi: Hour
9F. 6	DD	all	Temp	Indoor Hi: Day
9F. 7	Dx	all	Temp	Indoor Lo: 'c' of <ab.c> C
9F. 7	xH	all	Temp	Indoor Hi: Month
9F. 8	BD	0-2,all	Temp	Indoor Lo: 'ab' of <ab.c> C
9F. 8	Bx	3	Temp	Indoor Lo: Sign 0=+, 1=-
9F. 9	DD	all	Temp	Indoor Lo: Minute
9F.10	DD	all	Temp	Indoor Lo: Hour
9F.11	DD	all	Temp	Indoor Lo: Day
9F.12	Dx	all	Temp	Indoor Alarm Hi: 'c' of 32<abc<122 deg F @ 1
9F.12	xH	all	Temp	Indoor Lo: Month
9F.13	BD	0,all	Temp	Indoor Alarm Hi: 'ab' of <abc> F
9F.13	Bx	1-3
9F.14	DD	all	Temp	Indoor Alarm Lo: 'bc' of 32<abc<122 deg F @ 1
9F.15	Bx	0,1
9F.15	Bx	2	Temp	Format: 0=degrees C, 1=degrees F
9F.15	Bx	3
9F.15	xB	0	Temp	Indoor Alarm Lo: 'a' of <abc> F
9F.15	xB	1-3
9F.16	DD	all	Temp	Outdoor: 'bc' of -40<ab.c<60 degrees C @ 0.1
9F.17	Dx	all	Temp	Outdoor Hi: 'c' of <ab.c> C
9F.17	xB	0-2	Temp	Outdoor: 'a' of <ab.c> C
9F.17	xB	3	Temp	Outdoor: Sign 0=+, 1=-
9F.18	BD	0-2,all	Temp	Outdoor Hi: 'ab' of <ab.c> C
9F.18	Bx	3	Temp	Outdoor Hi: Sign 0=+, 1=-
9F.19	DD	all	Temp	Outdoor Hi: Minute
9F.20	DD	all	Temp	Outdoor Hi: Hour
9F.21	DD	all	Temp	Outdoor Hi: Day
9F.22	Dx	all	Temp	Outdoor Lo: 'c' of <ab.c> C
9F.22	xH	all	Temp	Outdoor Hi: Month
9F.23	BD	0-2,all	Temp	Outdoor Lo: 'ab' of <ab.c> C
9F.23	Bx	3	Temp	Outdoor Lo: Sign 0=+, 1=-
9F.24	DD	all	Temp	Outdoor Lo: Minute
9F.25	DD	all	Temp	Outdoor Lo: Hour
9F.26	DD	all	Temp	Outdoor Lo: Day
9F.27	Dx	all	Temp	Outdoor Alarm Hi: 'c' of -40<abc<140 deg F @ 1
9F.27	xH	all	Temp	Outdoor Lo: Month
9F.28	BD	0,all	Temp	Outdoor Alarm Hi: 'ab' of <abc> F
9F.28	Bx	1,2
9F.28	Bx	3	Temp	Outdoor Alarm Hi: Sign 0=+, 1=-
9F.29	DD	all	Temp	Outdoor Alarm Lo: 'bc' of <abc> F
9F.30	Bx	all
9F.30	xB	0	Temp	Outdoor Alarm Lo: 'a' of <abc> F
9F.30	xB	1,2
9F.30	xB	3	Temp	Outdoor Alarm Lo: Sign 0=+ 1=-
9F.31	BB	all
9F.32	Bx	0,1	Temp	Temp Outdoors Alarm Set when both bits=1
9F.32	Bx	2,3	Temp	Temp Indoors Alarm Set when both bits=1
9F.32	xB	all
9F.33	HH	all	Cksum	unsigned sum of first 33 bytes


AF. 0	HH	all	Group	AF ----------------------------------------
AF. 1	DD	all	Barom	Local: 'cd' of 795<abcd<1050 mb @ 1
AF. 2	DD	all	Barom	Local: 'ab' of <abcd> mb
AF. 3	DD	all	Barom	SeaLevel: 'de' of 795<abcd.e<1050 mb @ 1
AF. 4	DD	all	Barom	SeaLevel: 'bc' of <abcd.e> mb
AF. 5	Bx	0,1	Barom	Format: 0=inches, 1=mm, 2=mb, 3=hpa
AF. 5	Bx	2,3
AF. 5	xD	all	Barom	SeaLevel: 'a' of <abcd.e> mb
AF. 6	Bx	0-2	Barom	Trend: 1=Raising, 2=Steady, 4=Falling
AF. 6	Bx	3
AF. 6	xB	all	Barom	Prediction: 1=Sunny, 2=Cloudy, 4=Partly, 8=Rain
AF. 7	DD	all	Dewpt	Indoor:    0<ab<47 degrees C @ 1
AF. 8	DD	all	Dewpt	Indoor Hi: <ab> C
AF. 9	DD	all	Dewpt	Indoor Hi: Minute
AF.10	DD	all	Dewpt	Indoor Hi: Hour
AF.11	DD	all	Dewpt	Indoor Hi: Day
AF.12	Dx	all	Dewpt	Indoor Lo: 'b' of <ab> C
AF.12	xH	all	Dewpt	Indoor Hi: Month
AF.13	Dx	all	Dewpt	Indoor Lo: Minute 'b' of <ab>
AF.13	xD	all	Dewpt	Indoor Lo: 'a' of <ab> C
AF.14	Dx	all	Dewpt	Indoor Lo: Hour   'b' of <ab>
AF.14	xD	all	Dewpt	Indoor Lo: Minute 'a' of <ab>
AF.15	Dx	all	Dewpt	Indoor Lo: Day    'b' of <ab>
AF.15	xD	all	Dewpt	Indoor Lo: Hour   'a' of <ab>
AF.16	Hx	all	Dewpt	Indoor Lo: Month
AF.16	xD	all	Dewpt	Indoor Lo: Day    'a' of <ab>
AF.17	Hx	all	Dewpt	Outdoor Alarm: 0=1 C ... F=16 C
AF.17	xH	all	Dewpt	Indoor  Alarm: 0=1 C ... F=16 C
AF.18	DD	all	Dewpt	Outdoor:    0<ab<56 degrees C @ 1
AF.19	DD	all	Dewpt	Outdoor Hi: <ab> C
AF.20	DD	all	Dewpt	Outdoor Hi: Minute
AF.21	DD	all	Dewpt	Outdoor Hi: Hour
AF.22	DD	all	Dewpt	Outdoor Hi: Day
AF.23	Dx	all	Dewpt	Outdoor Lo: 'b' of <ab> C
AF.23	xH	all	Dewpt	Outdoor Hi: Month
AF.24	Dx	all	Dewpt	Outdoor Lo: Minute 'b' of <ab>
AF.24	xD	all	Dewpt	Outdoor Lo: 'a' of <ab> C
AF.25	Dx	all	Dewpt	Outdoor Lo: Hour   'b' of <ab>
AF.25	xD	all	Dewpt	Outdoor Lo: Minute 'a' of <ab>
AF.26	Dx	all	Dewpt	Outdoor Lo: Day    'b' of <ab>
AF.26	xD	all	Dewpt	Outdoor Lo: Hour   'a' of <ab>
AF.27	Hx	all	Dewpt	Outdoor Lo: Month
AF.27	xD	all	Dewpt	Outdoor Lo: Day    'a' of <ab>
AF.28	Bx	0	Dewpt   Outdoor Lo: O.R. = 1
AF.28	Bx	1
AF.28	Bx	2	Dewpt   Outdoor: O.R. = 1
AF.28	Bx	3	Dewpt   Indoor Lo: O.R. = 1
AF.28	Bx	0
AF.28	Bx	1	Dewpt   Indoor: O.R. = 1
AF.28	Bx	2,3
AF.29	Bx	0
AF.29	Bx	1,2	Dewpt	In and Out Alarm Set when both bits=1
AF.29	Bx	3	Barom	Alarm Set = 1
AF.29	xH	all	Barom	Alarm: 0=1mb ... F=16mb
AF.30	HH	all	Cksum	unsigned sum of first 30 bytes


BF. 0	HH	all	Group	BF ----------------------------------------
BF. 1	DD	all	Rain	Rate: 'bc' of 0<abc<998 mm/hr @ 1
BF. 2	Bx	all
BF. 2	xD	all	Rain	Rate: 'a' of <abc> mm/hr
BF. 3	DD	all	Rain	Yesterday: 'cd' of 0<abcd<9999 mm @ 1
BF. 4	DD	all	Rain	Yesterday: 'ab' of <abcd> mm
BF. 5	DD	all	Rain	Total: 'cd' of <abcd> mm
BF. 6	DD	all	Rain	Total: 'ab' of <abcd> mm
BF. 7	DD	all	Rain	Reset: Minute
BF. 8	DD	all	Rain	Reset: Hour
BF. 9	DD	all	Rain	Reset: Day
BF.10	Bx	0
BF.10	Bx	1	Rain	Format: 0=mm, 1=inches
BF.10	Bx	2,3
BF.10	xH	all	Rain	Reset: Month
BF.11	DD	all	Rain	Alarm: 'bc' of 0<ab.c<39.3 in/hr @ 0.1
BF.12	Bx	0	Rain	Alarm Set = 1
BF.12	Bx	1-2
BF.12	Bx	3	Rain	Rate: O.R. = 1
BF.12	xD	all	Rain	Rate Alarm: 'a' of <ab.c> in/hr
BF.13	HH	all	Cksum	Unsigned sum of first 13 bytes


CF. 0	HH	all	Group	CF ----------------------------------------
CF. 1	DD	all	Wind	Gust Speed: 'bc' of 0<ab.c<56 m/s @ 0.2
CF. 2	Dx	all	Wind	Gust Dir:   'c' of 0<abc<359 degrees @ 1
CF. 2	xD	all	Wind	Gust Speed: 'a' of <ab.c> m/s
CF. 3	DD	all	Wind	Gust Dir:   'ab' of <abc>
CF. 4	DD	all	Wind	Avg Speed:  'bc' of 0<ab.c<56 m/s @ 0.1
CF. 5	Dx	all	Wind	Avg Dir:    'c' of <abc>
CF. 5	xD	all	Wind	Avg Speed:  'a' of <ab.c> m/s
CF. 6	DD	all	Wind	Avg Dir:    'ab' of <abc>
CF. 7	DD	all	Wind	Hi Speed:   'bc' of <ab.c> m/s
CF. 8	Dx	all	Wind	Hi Dir:     'c' of <abc>
CF. 8	xD	all	Wind	Hi Speed:   'a' of <ab.c> m/s
CF. 9	DD	all	Wind	Hi Dir:     'ab' of <abc>
CF.10	DD	all	Wind	Hi: Minute
CF.11	DD	all	Wind	Hi: Hour
CF.12	DD	all	Wind	Hi: Day
CF.13	Dx	all	Wind	Alarm: 'c' of 0<abc<125 mph @ 1
CF.13	xH	all	Wind	Hi: Month
CF.14	Bx	1-3
CF.14	BD	0,all	Wind	Alarm: 'ab' of <abc> mph
CF.15	Bx	1
CF.15	Bx	2,3	Wind	Format: 0=mph, 1=knots, 2=m/s, 3=kph
CF.15	xB	all
CF.16	DD	all	Chill	Temp: -85<ab<60 degrees C @ 1
CF.17	DD	all	Chill	Lo: <ab> C
CF.18	DD	all	Chill	Lo: Minute
CF.19	DD	all	Chill	Lo: Hour
CF.20	DD	all	Chill	Lo: Day
CF.21	Bx	0	Chill	Lo: Sign 0=+, 1=-
CF.21	Bx	1	Chill	Temp: Sign 0=+, 1=-
CF.21	Bx	2,3
CF.21	xH	all	Chill	Lo: Month
CF.22	DD	all	Chill	Alarm: 'bc' of -121<abc<140 degrees F @ 1
CF.23	Bx	0	Chill	Alarm: 'a' of <abc> F
CF.23	Bx	1
CF.23	Bx	2	General	Power Source 0=AC, 1=DC
CF.23	Bx	3	General	Low Battery Indicator = 1
CF.23	xB	0-2
CF.23	xB	3	Chill	Alarm: Sign 0=+, 1=-
CF.24	Bx	0-2	General	Display Selected: 0=Time, 1=Temp ... 7=Rain
CF.24	Bx	3
CF.24	xB	0,1	General	Display Subscreen: 0=first ... 3=fourth
CF.24	xB	2,3	General	Display: 0=main, 1=mem, 2=alarm.in, 3=alarm.out
CF.25	Bx	0
CF.25	Bx	1	Wind	Hi Speed: O.R. = 1
CF.25	Bx	2	Wind	Avg Speed: O.R. = 1
CF.25	Bx	3	Wind	Gust Speed: O.R. = 1
CF.25	xB	0
CF.25	xB	1	Chill	Alarm Set = 1
CF.25	xB	2	Wind	Alarm Set = 1
CF.25	xB	3
CF.26	HH	all	Cksum	Unsigned sum of first 26 bytes

======================================================================

Nibble Column:
D-> 4 bit decimal number Range: 0-9
H-> 4 bit hex number Range: 0-15
B-> Bit encoded value Range: Variable
x-> Not defined in this entry

Bits Column:
Bits within defined Nibbles
0 - Lo order
3 - Hi order

General
All data is sent in the units shown and is independent of the units selected.
Data is sent 9600 baud 8n1.
Sensors that are not functioning or are out of range will return 'EE' as
the measurement.

Cksum

The last byte in each group is a checksum of that group. It is
calculated by performing an unsigned add of all the bytes in the
group, including the group number but not the checksum byte. The
checksum is the lo-order byte of the sum.

Group Info
Group   Length  Report  Contents
Number  (Bytes) Intervl Summary
8F      35      10 Sec  Time, Humidity
9F      34      10 Sec  Temperature
AF      31      10 Sec  Barometer, Dew Point
BF      14      10 Sec  Rain
CF      27      5 Sec   Wind, Wind Chill

Contributors:  Mike Wingstrom <mikeasl@ameritech.net> (Most of the hard work)
               Glynne Tolar <glynne@pdq.net> (alarms and misc.)
               Tim Witham - FES <twitham@pcocd2.intel.com> (listing format,
                                                            fixing of errors and misc.)