Hill-Rom Advanta P1600, Service Manual

Page: 176 / 429

ZoneAire® Sleep Surface Software Theory of Operation
Chapter 3: Theory of Operation
Page 3 - 38 Advanta™ Bed Service Manual (man168ra)
In all modes, the footboard control panel is monitored for activity pertaining to
the air system. In all modes, except the off mode, a main loop is executed at an
approximate 25 Hz rate that performs the following functions:
• Regulates/controls pressure in the appropriate air system mode
• Converts from a digital to an analog signal to calibrate each sensor prior to
an anaolg-to-digital conversion
• Converts from an analog to a digital signal on each pressure sensor
• Monitors electrical connection between the control circuit board and the
pressure sensing circuit board
• Monitors CPR switch input
• Monitors the driver circuits for the air pump and each valve for proper
output
Some operating modes have a mode memory feature. With this feature, the
system can return to the previous operating mode when the present mode’s
switch is pressed (i.e., toggle from the present mode back to the previous
mode). For example, suppose a transition is made to the auto firm mode from
the comfort mode. If the auto firm switch is pressed, a transition is made back
to the comfort mode and user-defined pressure trim points (defined below) are
restored. The following modes have this mode memory feature:
• Heel relief_1 mode
• Heel relief_2 mode
• Heel relief_3 mode
• Auto firm mode
• CPR mode
Off Mode
While in the off mode:
• The relay is opened.
• Other outputs are cleared.
• Hardware watchdog is refreshed (unless disabled by LON explicit message
code 0x01 for testing during manufacture).
• All air system footboard control panel activity is monitored.
• All air system LEDs, except mains power, are off.
• No pressure is regulated.