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Measurement Specialties Inc. NetScanner System (9016, 9021, & 9022) User’s Manual

3 - 8

3.1.4.1 Startup 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 NetScanner



System 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module is to notice that the TCP/IP socket connection is no longer valid.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 a

non-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).

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Pressure Systems 9022 Manuel d'utilisateur Page 41