Honeywell PPT User Manual page 64

P3 Pressure, Single, Binary Format
The P3 command produces a single temperature compensated pressure reading in a 6 byte binary
format; a 1 byte header character, 4 bytes encoded address and pressure data, and a1 byte <cr>
character (see Section 5.6—Binary Format Replies). Refer to Table 4.2 for default decimal placement
and significant digits.
When this command has a group or global address (dd=90-99), it is a sequential request command.
When this command has a group or global address (*9d), it is a sequential request command and the
OP=A or U 'all or changes only' parameter controls the output. If this command is executed while a
P2, P4, T2, or T4 command is executing, then one ASCII pressure reading is transmitted and the
continuous command resumes operation. When
analog reading value with a tilde '~' header - see '~' command at the end of this section.
The OP command also controls whether an integrity checksum is to be inserted between the last
data byte and the <cr> character. See OP command for checksum calculation.
Note: See the two notes in P1 command
Inquiry: *ddP3
Typical reply:
If reply is
P 4 Pressure, Continuous, Binary Format
The P4 command produces a continuous stream of temperature compensated pressure readings in a
6 byte binary format; a 1 byte header character, 4 bytes encoded address and pressure data, and a
<cr> character (see Section 5.6—Binary Format Replies). See P3 for typical reply. See the DO=P or
N commands for suspend readings from a P4 command.
When DA={O|S|T|U}, this command transmits the analog reading value with a tilde '~' header -
see '~' command at end of command section. For RS-485 mode, the TO=C command must be set to
transmit continuous readings.
The OP command also controls whether an integrity checksum is to be inserted between the last
data byte and the <cr> character. See OP command for checksum calculation.
Inquiry: *ddP4
Type: $*ddIN or *ddIN
Type: $*99IN or *99IN
Note: For RS-485 units, when the continuous transmit parameter is NOT active (is not set to
TO=C), the P4 command sends only one reading.
Note: For RS-232 units, type a $*ddIN to stop this command. The '$' character suspends the pres-
sure readings while the *ddIN command disables the continuous output function. For RS-485 units
when TO=C, type a *ddIN to stop this command.
Binary format compensated pressure reading from device ID=01
{@#16
is 15.478 inH
xx??? or (Binary format compensated pressure reading not available yet,
xx_?? request again, or it has been disabled. The 'xx' is the header
character and the 6 most significant bits of the address.
To stop a single PPT from continuous pressure reading.
To stop the continuous readings for all PPTs on the bus.
5 8
DA={O|S|T|U}, this command transmits the
O; refer to Table 5.1 and 5.2
2