Intek RheoVac DR - Manual (Page 17)

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3.7 CUSTOM SOFTWARE
Custom software may be developed by the user to receive and archive RheoVac DR data into a computer
system. The electronics has a serial data protocol of 9600 baud, no parity check, eight data bits and one
stop bit (i.e., 9600,N,8,1). Each transmitted group of data is sent in a standard ASCII coded format
representing each process variable value, instrument identification and status information.
The data stream consists of 13 fields, followed by a carriage return <RETURN>. The first ten fields,
nine bytes each, are the process values. Following the process variables are the RheoVac serial number,
nine bytes, the process identification tag number, 15 bytes, and the RheoVac system status, seven bytes.
The data stream is then ended by a single <RETURN> byte (ASCII code 13). The total number of bytes
transmitted in each data stream is 122 bytes per probe including the trailing <RETURN>. This data
group is sent approximately once every three seconds. Table V shows the field names and number of
bytes in one data stream.
TABLE V. Serial Output Data Stream
Actual
Volume
Flow
(A CFM )
Total
Mass
Flow
(lbs/hr)
Water
Vapor
Flow
(lbs/hr)
RheoVac
Press ure
("Hg abs)
Water
Vapor
Sp . V ol.
(Cu. ft/lb)
W ater to
Air Mass
Ra tio
(lb/lb)
Relative
Saturation
( %)
H
2
O
Partial
Press ure
("Hg abs)
Air
Mass
Flow
(lb/hr)
Probe
Temp.
(°F)
Instr.
Serial
Number
ID
Tag
No.
Status
Term.
< C R >
9
bytes
9
bytes
9
bytes
9
bytes
9
bytes
9
bytes
9
bytes
9
bytes
9
bytes
9
bytes
9
bytes
15
bytes
7
bytes
1
byte
Each of the first ten process values are sent in the fixed decimal format of XXXX.XXXX with leading
and trailing zeros inserted to maintain the nine character length. The next three fields are ASCII text
strings followed by the <RETURN>. Example: The nine bytes for an air mass flow of 10.0 lb/hr would
be: 0010.0000, or 48,48,49,48,46,48,48,48,48 ASCII.