Pressure Systems, Inc. | Model 9116 User’s Manual |
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3.1.4.1Startup Initialization
Since power supplies may be distributed widely across a network of modules and host computer(s), it is not uncommon for modules (singly or together) and the host to lose power independently. Thus, their power may be restored at different times. Startup initialization, for every module, must normally be performed when its power is restored, as each module enters default states after power-up, which may not be the state the host computer had previously been operating in. Any previous TCP/IP socket connection is also lost after power failure and must be re-established between host and module before any TCP/IP commands can be recognized by the module. These commands are generally used to detect that startup initialization has occurred (or to force reset at other times), after which other commands may be used to restore the original operating condition.
With Model 9116 modules, the Power-Up Clear (‘A’) command is used as a simple command to elicit a known response from a module. Although this causes no internal function within the module, it will result in an acknowledgment being returned to the host computer to verify proper communications. The best way to detect that a power reset has occurred in a module is to notice that the TCP/IP socket connection is no longer valid. At any point during module operation, the Reset (‘B’) command may be used to return any module to its default “reset” state. If the module is then required to enter any other states (that were previously programmed for it by the host), the host must then restore these states accordingly using the appropriate commands. This reset command simply returns internal software parameters to a default state (as after power up or reboot). It will not close the existing TCP/IP socket (as will power up or reboot).
The Set/Do Operating Options/Functions (‘w’) command has many purposes, but may first be utilized during the module initialization stage. It may also be executed at any time during data acquisition. However, some non-factory-default options of ‘w’ may become the new reset default, if a particular function is used to establish them in non-volatile memory.
If any form of the Configure/Control Autonomous Host Streams (‘c’) command or the Configure/Control Multi-Point Calibration (‘C’) command was in use before reset, it must be executed again after the reset to restore it. Any other command, that establishes the module in
anon-default reset state, must be re-executed after a reset, if processing is to continue in that state.
The Network Query (“psi9000”) UDP/IP command may be used (at any time) to make each module on the network identify itself to the host(s). A parameter, returned in each module’s response, indicates whether or not a module still has a valid connection. This is a useful way to detect if an overt reset occurs in a module. The module may be configured to emit this response automatically after any reset (power on or reboot).
3.1.4.2Module Data Acquisition
After power-up, all modules will begin to scan all attached transducer channels in channel number order. Scanning will occur at the module’s maximum internal rate (using the previously stored number of data averages per channel). The data are stored in an internal buffer, available for retrieval by the host computer. Engineering units conversion of the scanned channels is accomplished using thermal correction data extracted from each transducer at power-up. While scanning, the module will automatically monitor the attached transducer’s temperature, correcting engineering unit output for any temperature effects.
