2.4
INITIAL TURN-ON RESPONSE
Analog Output
The analog output will provide a voltage (range 0-5V) which, when no pressure is applied to the
PPT, reads:
Voltage Output
Pressure Type
Gauge units
Differential units
Absolute units
Digital Output
(@ zero applied pressure)
0 volt
2.5 volts
A voltage representing atmospheric pressure
Once the wiring connections and terminal program settings are complete, the PPT will automati-
cally send the following response (or similar to) when power is applied. This reply will be gener-
ated any time power is applied to the PPT.
Typical Reply:
RS-232
?01PPT____10__psid
RS-485
?00PPT____10__psid
The “
?01
” or “
?00
” indicates a default address device called a “null address”. This PPT has not yet
been assigned an ID number so it assumes the null address. The “
PPT____10__psid
” indicates a
10 psi differential device.
2.5
COMMAND FORMAT
Any command interaction with the PPT requires electrical connection to the RS-232 or RS-485
serial communications pins. There are two basic types of commands – action directing commands
and information requesting commands. Theses are described in
Commands – Section 5.
Typical PPT commands have the form
*ddcc = nnn
<cr>
Where: *
dd
cc
=
nnn
<cr>
is the command header character
is the decimal address of the PPT
is a command (refer to Commands – Section 5 for a complete
description of commands)
equal sign (required in some commands)
additional characters (required in some commands)
carriage return is required to end all commands
(do not type, press the ENTER/RETURN key)
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