- 49 -
18. CUSTOM ASCII PROTOCOL TRANSMITTER COMMUNICATIONS
1.0
SERIAL COMMUNICATION FORMAT
Mode ................ Full Duplex (Separate transmit and receive lines) and Half Duplex (RS485 only)
Baud Rate ......... 300, 600, 1200, 2400, 4800, 9600, 19200 selectable with Instrument Setup
software.
Parity ................ None
Word length ...... 8 data bits
Stop bit ............ 1
The Custom ASCII protocol is simpler than the Modbus protocol. This 5-page manual section
provides some of its key programmable features. Our detailed Serial Communications manual
can be downloaded from http://www.laurels.com/downloadfiles/serialcom2.pdf
http://www.laurels.com/downloadfiles/serialcom2.pdf
http://www.laurels.com/downloadfiles/serialcom2.pdf
http://www.laurels.com/downloadfiles/serialcom2.pdf
2.0
MEASUREMENT DATA FORMAT
The basic measurement data format consists of 8 ASCII characters for analog input “DPM”
transmitters, such as +999.99<CR>, where <CR> is the carriage return character. The first
character is always a plus or minus sign. A decimal point is always furnished, even when it
follows the last digit.
Adding a Line Feed Character to the Basic Format:
Printers and other devices that receive the
data may require a line feed character <LF> following the <CR>. The line feed character <LF>
may be selected using Instrument Setup software.
Adding a Coded Data Character to the Basic Format:
A coded character from A to H may be
added to the data string according to the table below to indicate the alarm and overload status
of the device. If used, this character precedes the <CR>, so that it is the last printable character
in the string. With the optional <LF> and coded character selected, the data string will consist
of 10 characters for analog input “DPM” transmitters, such as +999.99A<CR><LF>.
Alarm Status
No Overload
Overload
Neither Alarm set
Alarm 1 set only
Alarm 2 set only
Both Alarms set
A
B
C
D
E
F
G
H
For example, a coded character “G” indicates that Alarm 2 only is set and that the transmitter is
in the overload condition. This information is useful when data is supplied to a computer for
listing and analysis, or when data is supplied to a Remote Display in a Master-Slave confi-
guration.