Agilent Technologies A.18.00 ユーザーズマニュアル

ページ / 581
 437
Chapter 8, Programming the Call Processing Subsystem
Using the Call Processing Subsystem’s Remote User Interface
When To Query Data Messages Received From The Mobile Station
The Call Processing Subsystem makes available to the control program many data 
messages received from the mobile station. For example, if the Test Set sends a 
registration message to the mobile station, the registration information (MIN, 
ESN, SCM) received from the mobile station can be read by the control program.
The data messages are displayed on the CRT after the successful completion of 
the call processing function (registration, page, origination, etc.). When call 
processing functions complete, state changes occur within the Call Processing 
Subsystem. For example, when a registration completes the Call Processing 
Subsystem exits the register state (the 
Register
 annunciator is turned off) and 
returns to the active state (the 
Active
 annunciator is turned on).
The control program should only query the Test Set for the data messages after all 
the state transitions are complete. For example, the control program should not 
attempt to read the MIN, ESN or SCM until after the 
Register
 annunciator is 
turned off and the 
Active
 annunciator is turned on. 
This is because the Test Set has a multitasking architecture wherein multiple 
processes execute on a priority driven and an event driven basis. Each process is 
given a timeslice on the CPU depending upon its priority, the priority of other 
processes and the nature of the events occurring within the Test Set.
Upon completion, processes within the Call Processing Subsystem pass data 
messages received from the mobile station to the Measurement Display Process 
which displays the information on the CRT during its next CPU timeslice. If the 
control program attempts to query the data fields before the Measurement Display 
Process has posted the information to the CRT, it is possible that the fields will be 
blank or contain data from a previous call processing function.
Waiting to read the data messages until after all state transitions have occurred 
ensures that the data from the most recent call processing function will have been 
posted. 
 lists 
the possible state transitions within the Call Processing Subsystem.