Rockwell-automation T8019 Trusted Process Control Algorithm Software P Manual do Utilizador descarregar pdf (Página 7)

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Process Control Algorithms T8019

Issue 8 Sep 07 PD-T8019 7

1. Description

Several of the basic control algorithms may generate error conditions at run-time as all function

arameters are variable. This may result in reversed parameters, e.g. max < min, overflow and

underflow conditions, divide by zero errors, etc. For each function, the required output under these

conditions is defined and error counters are incremented. These error counters are available to the

application programmer using the error statistics function block.

The function block has a single Boolean input that is used to reset the counters. Whilst this input is

true, the error counters will be reset to zero. The initial value of all error counters is zero.

ERRSTAT

RESET

Overflow

Param

eversed

Zero Divide

Underflow

Data types are

1. RESET Boolean

2. All others Integer

Output Error condition

Reversed Pairs of function parameters are reversed, i.e. max<min.

The associated function has reversed the two values in order

to obtain a valid result. The count is incremented on each

iteration of the function whilst the parameters are reversed.

Param A function parameter is incorrect, e.g. out of range or not

consistent with the functions required operation. The count

is incremented on each iteration of the function whilst the

parameter is incorrect.

Overflow An overflow error occurred in the execution of the function.

The count is incremented on each iteration of the function

whilst the overflow condition occurs.

Underflow An underflow error occurred in the execution of the function.

The count is incremented on each iteration of the function

whilst the underflow condition occurs.

Zero Divide A divide by zero error occurred in the execution of the

function. The count is incremented on each iteration of the

function whilst the divide by zero condition occurs.

Table 1 Error Statistics

1 2 3 4 5 6 7 8 9 10 11 12 ... 27 28

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Rockwell-automation T8019 Trusted Process Control Algorithm Software P Manual do Utilizador Página 7