Rockwell Automation T80017 Application Note Regent to Trusted Migration - Manual (Page 8)

Trusted TM
AN-T80017 Regent to Trusted Migration
Issue 2 June 08 AN-T80017 8
Channel LEDs may be prevented from showing faults using the MONITOR_MASK as in Winterpret.
The digital input monitoring thresholds are also entered on board parameters, as are any other
parameters required in the Winterpret application.
4.3. Declaration of variables
In Regent, the Modbus address map is automatically assigned to variables according to their position
in the list. This often means that spare variables must be declared to fill in gaps between address
blocks. In Trusted, each variable is assigned an address separately, and so spare variables are not
necessary.
PD-T8160 describes the connection points available on each I/O module definition. These may be
different to Regent. For example, digital inputs in Regent can be read individually using digital shared
control relays and also as a 16-bit word using shared registers. The definitions in Trusted will arrange
the data differently, including differences for definitions connecting to single, dual and triple module
sets and for open and packed data.
4.4. Replacement of Scale function blocks
Winterpret applications can have SCALE function blocks which convert input signals (as 0-4095) into
engineering units, including square root extraction if necessary. These may be replaced using
conversion tables in the Trusted analogue dictionary. The values and data available to the Regent
application will be in the same format and scaling in the Trusted application.
4.5. Replacement of Ladder function blocks
Winterpret has a fixed grid for its ladder logic with ten columns, the last of which must be a coil output.
The Trusted Toolset can handle ladder programs in two different editors. The Function Block Diagram
editor can program ladder logic using a switch on the toolbar. In this editor, ladder elements can be
placed anywhere on the screen and wired together; the left-hand inputs must be wired from a power
rail element. Essentially this is function block diagram programming using elements that look and act
like ladder logic elements.
There is also a ‘Quick LD’ editor, which allows creation and insertion of ladder elements and rungs,
automatically arranging branches in a fixed format. This may prove quicker to some programmers, but
it does not allow the flexibility of FBD ladder arrangement.
Trusted FBD ladder is executed according to the hierarchy of inputs; a block will not execute until its
inputs are ready. The program execution will therefore work its way from farthest inputs through to final
outputs.
Regent ladder executes down each column in turn for each rung. It is possible to create logic which
relies on this execution order for its operation. Therefore be aware that Trusted FBD ladder may
interpret the execution order differently to Winterpret ladder. The FBD editor has an option ‘Show
Execution Order’ which numbers function blocks and outputs in the order they are executed. Moving
logic on the screen may change this order but it is best practice to separate rungs to force the
execution order because in either language, the rungs are executed in order from top to bottom.
Regent function blocks are described in the Regent Software reference manual. The most common
complication is timers. Winterpret has one timer block with inputs for ‘time’ (increment the
accumulator) and ‘enable’ (allow incrementing when true or reset the count when false). Usually these
inputs are shorted together, so it acts as a delay-on timer like Trusted’s TON, but they may be
separate. If separate, the timer will be part of a latch to define other actions like TP. It has two outputs
which are the permanent inverse of each other; the upper output goes true on timeout.