Implementation-dependent parameters

IEC compliance table for implementation-dependent parameters:

Parameters

Limitations/Behavior

Maximum length of identifiers

32 characters

Maximum comment length

Within the Control Expert: 1024 characters for each editor object.

Import: limited by XML constraints or UDBString usage in the persistent layer.

Syntax and semantics of pragmas

Unity Pro V1.0 only implements 1 pragma, used for legacy convertor:

{ ConvError (' error text'); }

any other pragma construct is ignored (a warning message is given)

NOTE:

Unity Pro is the former name of Control Expert for version 13.1 or earlier.

Syntax and semantics for the use of the double-quote character when a particular implementation supports Feature #4 but not Feature #2 of Table 5.

(#2 of table 5 is supported)

Range of values and precision of representation for variables of type TIME, DATE, TIME_OF_DAY and DATE_AND_TIME

for TIME : t#0ms .. t#4294967295ms

(=t#49D_17H_2M_47S_295MS)

for DATE: D#1990-01-01 .. D#2099-12-31

for TOD: TOD#00:00:00 .. TOD#23:59:59

Precision of representation of seconds in types TIME, TIME_OF_DAY and DATE_AND_TIME

TIME: precision 1 ms

TIME_OF_DAY: precision 1 s

Maximum number of enumerated values

Not applicable

Maximum number of array subscripts

6

Maximum array size

64 kbytes

Maximum number of structure elements

no limit

Maximum structure size

no limit

Maximum range of subscript values

DINT range

Maximum number of levels of nested structures

10

Default maximum length of STRING and WSTRING variables

16 characters

Maximum allowed length of STRING and WSTRING variables

64 kbytes

Maximum number of hierarchical levels

Logical or physical mapping

Premium: physical mapping (5 levels)

Quantum: logical mapping (1 level)

Maximum number of inputs of extensible functions

The number of all input parameters (including in-out parameters) is limited to 32. The number of all output parameters (including in-out parameters) is also limited to 32.

Thus the limit for extensible input parameters is (32 - number of input parameters - number of in-out parameters).

The limit for extensible output parameters is (32 - number of output parameters - number of in-out parameters).

Effects of type conversions on accuracy

See online help.

Error conditions during type conversions

Error conditions are described in the online-help. Globally %S18 is set for overflow errors detected. ENO is also set. The result is depending on the specific function.

Accuracy of numerical functions

INTEL floating point processing or emulation.

Effects of type conversions between time data types and other data types not defined in Table 30

See online help.

Maximum number of function block specifications and instantiations

Only limited by the maximum size of a section.

Function block input variable assignment when EN is FALSE

No assignment

Pvmin, Pvmax of counters

INT base counters:

  • Pvmin=-32768 (0x8000)

  • Pvmax=32767 (0x7FFF)

UINT base counters:

  • Pvmin=0 (0x0)

  • Pvmax=65535 (0xFFFF)

DINT base counters:

  • Pvmin= -2147483648 (0x80000000)

  • Pvmax=2147483647 (0x7FFFFFFF)

UDINT base counters:

  • Pvmin=0 (0x0)

  • Pvmax=4294967295 (0xFFFFFFFF)

Effect of a change in the value of a PT input during a timing operation

The new PT values are immediately taken at once into account, even during a running timing operation immediately works with the new values.

Program size limitations

Depends on controller type and memory

Precision of step elapsed time

10 ms

Maximum number of steps per SFC

1024 steps per SFC section

Maximum number of transitions per SFC and per step

Limited by the available area for entering steps/transitions and by the maximum number of steps per SFC section (1024 Steps).

32 transition per step. Limited by the available area for entering Alternative/Parallel branches, maximum is 32 rows.

Maximum number of action blocks per step

20

Access to the functional equivalent of the Q or A outputs

not applicable

Transition clearing time

Target dependent;

always < 100 micro-seconds

Maximum width of diverge/converge constructs

32

Contents of RESOURCE libraries

Not applicable

Effect of using READ_WRITE access to function block outputs

Not applicable

Maximum number of tasks

Depends on controller type.

Maximum on most powerful controller: 9 tasks

Task interval resolution

10 ms

Maximum length of expressions

Practically no limit

Maximum length of statements

Practically no limit

Maximum number of CASE selections

Practically no limit

Value of control variable upon termination of FOR loop

Undefined

Restrictions on network topology

No restrictions

Evaluation order of feedback loops

The block connected to the feedback variable is executed first