ProSoft Technology ProSoft i-View - Manual (Page 52)

Data Source Files ProSoft i-View ♦ Mobile Process Monitoring and Control Application
User Manual Version 2.0.2
Page 52 of 106 ProSoft Technology, Inc.
September 29, 2011
System Variables
There are a number of system variables that can be used in expressions as if they would
be regular tags. The following variables are provided.
$SMPulse10s
$SMPulse30s
$SMPulse60s Number
(read only) They generate a square wave signal with the period implicit on
the variable name. They can be used to implement a Keep-Alive
tag, to write periodically a value on a PLC, or to trigger periodic
events for any purpose.
$SMAckButton Number
(read only) Variable linked to the Acknowledge button on the alarms panel.
Goes to 1 when the button is pushed and 0 when it is released.
$SMCommState Number
(read only) A value indicating the current communication state of ProSoft i-
View. Possible values are the following:
0 - Communications running with all PLC connections linked.
1 - Monitor is switched off.
2 - One or more PLC are not linked or a new connection is in
course. Partial link state.
3 - General communications error. No communication is
established.
This variable can be used to implement alarms related to PLC
reachability or to show/hide interface elements depending on
PLC availability.
$SMCurrentPage-
Name String
(read/write) Name of currently displayed page
$SMDate String
(read only) Twext representation of the current date and time in the
following format “yyyy-mm-dd-hh-mm-ss”
Functions Methods, and more about Operators
Methods can be applied to intermediate expressions or variables to perform type
conversions or to achieve particular requirements. They are like computer
language functions that perform particular tasks. Not all methods are applicable
to all types and their meaning can vary depending on type. Methods are invoked
by appending a dot (method selector operator) followed by its name to the
variable or subexpression they apply to.
Operators can also have a different meaning depending on the type of data they
are applied to.
In the following tables we represent the meaning of the applicable operators and
methods depending on data type.