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ADS-14221, PPT2 User Manual
COMMAND FORMAT
Communication between the host or control processor and a PPT2 is accomplished by message transfers, or
commands and replies. Communications initiated by the host processor to one or more PPT2s are called
commands and must begin with an '*' header character. (For RS-485 PPT2s, alternate header characters are
available, using the MO command.) All commands must be terminated by a <cr> (carriage return or ENTER key).
Communications initiated by a PPT2 to the host are called responses or replies, and begin with one of ten unique
header characters (2 for ASCII responses, 8 for binary format responses).
Commands may request information from one or more PPT2s such as read pressure, or direct action to one or
more PPT2s such as change a command value or operating mode.
Typical PPT2 command format:
Where: *
dd
cc
=
nnn
<cr>
Note: For RS-485 mode, alternate headers are available. (see MO command)
In an RS-232 network, when manually applying commands to one or more PPT2s which are in the continuous
send mode (P2, P4, T2, ), the special header character '$' should be used to suspend all PPT2 transmissions
while the command message is being typed. The '$' is immediately followed by the normal command format.
In the case of an RS-232 network, if an erroneous command is sent to the PPT2, it is echoed back to the host as
soon as the PPT2 recognizes it as an invalid command. For example, if the user tries to enter *01S2=15 (S2 is
not a valid command for the PPT2), *01S2 would immediately be echoed back. The other instance of an echoed
command is when a group or global address command (ID = 90 to 99) is sent, such as *99I=R15<cr>.
Group/global addresses will always echo the command back to the host processor after being read by all PPT2s
in the network.
*ddcc = nnn <cr>
is the command header character
is the decimal address of the command message (00-99)
is the command code. Command code characters sent to the PPT2 are not case
sensitive; i.e.,
either an upper case or lower case may be used. Responses from the PPT2 will have
capitalized command code characters. Example: #01CP=14.2426
equal sign (required in some commands)
additional characters (required in some commands)
carriage return (the ENTER key on a standard keyboard)
October, 2016
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