67
FXB communication
Table 34 Data record element descriptions
Information Description
Status
When translated to a binary byte, the status character indicates the status of the counter.
As shown below, ASCII character "$" has a decimal value of 36, which when converted to a
binary byte, sets the third and sixth (always 1) bits. Bit 0 is considered to be the first bit.
ASCII character Meaning Decimal equivalent
Binary equivalent
(bit 76543210)
(blank space) No alarms 32 00100000
! Check sensor 33 00100001
$ Alarm/count alarm 36 00100100
% Check sensor and alarm 37 00100101
` Air flow alarm 96 01100000
Date
Date information is carried in the third through eighth characters of the record. The second
character is always a space, to separate the status character from the date characters. The
date is arranged as MMDDYY (Month Day Year). In the serial communications example on
the previous page, the date is August 1, 1999 (the day the counter collected the data).
Time
Time information is carried in the tenth through the fifteenth characters of the record. The
ninth character is always a space, to separate the date from the time. The time is arranged
as HHMMSS (Hours Minutes Seconds) military time. In the example on the previous page
the time is 9:52 A.M. and 50 seconds.
Period
The period is the sample time or the length of counting time. The period information is
carried in the seventeenth through twentieth characters. The sixteenth character is always
a space, to separate the time and period. The period is presented in minutes and seconds.
In the example on the previous page the period was 0130 or one minute, 30 seconds.
When the period is controlled by the computer (c command), the period characters will be
zeros. When the period is controlled by the counter (d command), the characters will
represent the sample time.
Tags
The tags contain three characters that identify the type of data that will follow. If the data is
particle count, the tag will indicate the particle size. If the data is location number, the tag is
called LOC. The data following the LOC tag will be the number programmed during setup
as the remote counter's location number (any identifying number from zero to 31 can be
assigned) will be indicated. Other tag examples:
FLO - Flow rate value in CFM. A value of 000100 equals .100 CFM. A value of 001000
equals 1.000 CFM. This flow tag is not available when operated in 48XX mode.
CAL - Calibration value of the sensor. A value of 000100 equals a calibration voltage of
1.00 VDC. Valid ranges are 0.80 to 1.20 VDC. A reported value outside this range will
cause a calibration alarm to be reported in the status byte.
TMP - Air temperature reading from the externally attached environmental probe. A value
of 000231 equals 23.1 °C.
R/H - Relative Humidity reading from the externally attached environmental probe. A value
of 000561 equals 56.1% RH.
Chan 1, Chan 2
These characters contain count data from the measurements the counter has made. The
size and count are each preceded by a space character for separation.
Size The size is three characters, preceded by a space, and indicates the particle size range.
Count
The count is six characters, preceded by a space, and indicates the number of particles
counted for the particle size range preceding the number. In the data string example in
Figure 29 on page 66, the count in the channel 1 size range was 5492 particles.
Location
A unique number assigned to each unit in multiple counter installations. The assigned
number applies to the "device" select code number and eliminates simultaneous talking on
the bus during serial networking of multiple counters.
Checksum
The checksum is a six-character hexadecimal number (with two leading zeros), preceded
by a three-character tag and a space. The numerical value of the checksum is equal to the
sum of the decimal equivalent of each ASCII character in the record, including spaces.
Used for testing accuracy of data transmission.
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