2 Theory of Operation1006-0836-000 02/03 2-72.3.2 MonitoringinterfaceThe Monitoring Interface Assembly (MIA) in the Aestiva machine or theVentilator Monitoring Board (VMB) in the Aespire machine serves as theinterface between the ventilator’s control board and the breathing systemsensors and switches:• the inspiratory and expiratory flow sensors• the O2 sensor• the Bag/Vent switch• Module ID board switches (for the Aestiva machine). The AespireVMB is hardwired to indicate a Circle module.• the canister release switch (in the Aestiva machine). The Aespiremachine does not indicate an open canister.• the absorber bypass switch (in the Aestiva machine).• the control panel switch (in the Aestiva machine). The Aespiremachine uses this signal to indicate that the ABS breathing systemis disengaged.• the Auxiliary Common Gas Outlet (ACGO) switchThe MIA for the Aestiva 7100 ventilator is located under the front and rearsubfloors of the breathing system (below the bulkhead). The VMB for theAespire 7100 ventilator is located under the tabletop (below theworksurface).2.3.3 Serial interface The Serial Adapter Board (SAB) in the Aestiva machine or the SerialInterface and Connection Board (SICB) in the Aespire machine provides twofunctions. It serves as the interface between the ventilator’s control board andadditional switches located in the machine and channels serialcommunications signals from the controller board to the RS232 connector.The machine switches include:• the System On/Standby switch• the O2 supply pressure switch• the O2 flush switchThe SICB in an Aespire machine also includes an on/off signal through theRS232 connector to a remote monitor.
