Page 5-6
MiniCapt Remote Microbial Air Sampler Operations Manual
Chapter 5 Modbus Protocol
Input Registers
30215:
Number of Data Samples in
the Queue
A value of zero is identical to no data available (same
meaning as coil 00/02 read as zero).
The queue size setting will determine if the data register
section shows real-time data or stored data. If the queue size
setting has been set to one, the sample data will always
represent the last real-time data packet and the queue value
will be set to one if there is a data packet available. If the
queue size setting is set greater than one, the sample data
will represent the last data queued and the queue value will
be set to one if there is any queued data available.
The two types of data presentation are supported by the
same Modbus register map and are delineated by how the
host system processes the register/coil fields and the
instrument queue setting. The data register section can be
forced to show real-time data by setting the queue size to one
or to show queued data by setting the queue size greater than
one. Queued data is always presented oldest first. The queue
size command is “set queue #” where # is a value between 1
and 3000.
30216 - 30217:
Time Stamp
Dual-register representation of data packet time stamp.
Integer value (type defined as time_t) representing start date/
time in seconds since January 1, 1970.
30218 - 30219:
Sample Time
Dual-register representation of data packet sample interval
processed in units of seconds. Can be integer or float
depending on mode selected. The integer representation is
time in seconds multiplied by 100.
30220- 30221:
Data Packet Status
Values are defined in
30222 - 30223:
Flow Rate
Dual-register representation of the real-time flow rate in liters
per minute. Can be integer or float depending on mode
selected. The integer representation uses the scale factor
from register 30011.
30224 - 30225:
Volume
Dual-register representation of the real-time volume in liters.
Can be integer or float depending on mode selected. The
integer representation uses the scale factor from register
30012.
30226:
Location
Index of location value associated with data packet. Not used
for MiniCapt.
30227:
Number of Particle Channels
Processed as a variable but fixed to a value of 0 for MiniCapt.
30228:
Number of Analog Channels
Processed as a variable but fixed to a value of 3 for MiniCapt.