Timing Diagrams; Figure 7.1 Default Single Pressure Reading Timing Diagram; Figure 7.2 Default Continuous Pressure Reading Timing Diagram; Figure 7.3 Continuous Pressure (With Ic = 1) Timing Diagram - Honeywell PPT User Manual

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TIMING DIAGRAMS

For the factory default settings, the PPT will respond to a P1 or P3 pressure reading with an integration
time of 200 msec at 9600 baud data output. The timing for this is shown Figure 7.1. The RS-232 com-
mand input time, Y, is the transmission time for the command message. This is equal to the number of
command characters plus the <cr> character, times the baud transmission time per byte (*01P1<cr> = 6
x (byte times)). The integration and calculation times are internal PPT times. The integration time is user
controlled with the DI command. The RS-232 pressure reading output time, X, is the reply transmission
time. Character, byte or transmission times for different baud rates are listed in Table 7.1. Reply charac-
ter lengths, X, are listed in Table 7.2.
When I=Mn mode or I=R30 (or less) mode:
For continuous pressure reading commands (P2 and P4), the PPT internal times and the output timing
are shown Figure 7.2.
For continuous pressure reading commands (P2 and
the output timing are shown Figure 7.3.
Shown below in Figures 7.4 to 7.6 are the timing diagrams for faster pressure output rates - up to 120
readings/second. These rates are achieved by setting the integration time (I=) command. For the con-
tinuous reading commands P2 and P4, three pressure output timing figures are shown below.
RS-232 Command Input
RS-232 Pressure Reading Output
Figure 7.1—Default Single Pressure Reading Timing Diagram
Integration period
Calculations 10 msec (nom.)
RS-232 Pressure Reading Output
16.7 msec
Figure 7.2—Default Continuous Pressure Reading Timing Diagram
Integration period
200 msec
Calculations 10 msec (nom.)
RS-232 Pressure Reading Output
16.7 msec
Figure 7.3—Continuous Pressure (with IC = 1) Timing Diagram
(See Tables 7.1 and 7.2 for X times)
200 200
msec msec
X msec
200 msec
(See Tables 7.1 and 7.2 for X times)
P4) and an IC=1 setting, the PPT internal times and
200 msec
X msec
400 msec
(See Tables 7.1 and 7.2 for X times)
76
Y msec
0-1 byte
X msec
. . .
200
msec
. . .
. . .
. . .
. . .
. . .