加载中…ABB_800xA学习笔记263：System_800xA_Control_6.0_AC_800M_Configuration53
(2023-12-17 19:03:24)
标签：
abbsystem_800xa_ac800m配置手册功能和组件 |
分类： ABBDCS |
继续学习ABB
800xA配置手册第一章功能和组件，进入第131页。
How does AC 800M handle the result
when result is out of limits
当结果超限时，AC 800N如何处理？
Arithmetical calculations near the
range limits will result in either overflow
or underflow.
数学计算接近范围限制将导致上溢或者下溢。
Division by zero will result in the largest
positive value if the numerator is
positive and the
largest negative value if the numerator is
negative.
如果分子为正数，除以零导致最大的正数，如果分子为负数，除以零将导致最大的负值。
In
some rare case could the result be NaN (Not a Number).
极少数情况下，结果是NaN(不是数字）
To
ensure that the result is proper values use the function RealInfo.
See online Help for details about RealInfo.
要确保结果是正确的值，使用函数RealInfo，有关RealInfo详细信息，请看联机帮助。
How to use floating point
如何使用浮点数
The
IEEE Standard for Floating-Point Arithmetic (IEEE 754) is a
technical standard for floating-point computation. A floating
point value has the type real
in
IEEE浮点计算标准（IEEE
754)是浮点数计算的技术标准。浮点数值在IEEE61131-3中为实数。
Arithmetic
算数
A
floating point value has typically 7 significant figures. If a big
and a small floating point value are added there is not enough
significant figures.
浮点数值通常有7个有效数值。如果将大浮点值和小浮点值相加，则没有足够有效数字。
Example:
例如：
An
accumulator r1 is incremented by a small value r2: "r1:= r1 + r2;".
It will work fine
when r1 is small but suddenly r1 won't increase anymore, and that
is because
累加器r1递增一个小值r2，r1:=r1+r2;
当r1很小，可以正常工作。但当和有太多有效数字就突然不再工作了。 例如，如果 r1 = 123456.0 和 r2 = 0.0009，则总和 r1 应为
123456.0009。If for instance
r1 = 123456.0 and r2 = 0.0009 the sum r1 should be
123456.0009.
The
solution is to use another accumulator that accumulates r2 up to a
size that could be
safely added to the final accumulator r1.
解决方案是使用另一个累加器，该累加器将 r2 累积到可以安全地添加到最终累加器 r1
的大小。
除法
Division by zero will result in the
largest positive value if the numerator is
positive and the
largest negative value if the numerator is negative.
如果分子为正数，除以零将得到最大的正值。如果分子为负数，则为最大负值。
比较
Don't do "b1:= r1 = r2;" to find out
if two floating point values are the same. r1
and r2 might be
shown as the same value but have different binary representation.
You
不要执行“b1：= r1 = r2;”来确定两个浮点值是否相同。R1 和 R2
可能显示为相同的值，但具有不同的二进制表示形式。您可能想执行类似“b1：= abs（r1 - r2） <
0.001;”
溢出
A floating point value might get the
special value "overflow" if for instance two
big values are
multiplied. Any subsequent use of an overflow value will result in
a new
例如，如果将两个大值相乘，浮点值可能会获得特殊值“溢出”。后续使用溢出值将导致新的溢出值。因此，一个溢出值可能分布在一个计算单元中，每个值都是一个溢出值。当存在操作可能产生溢出的风险时，可以使用函数
RealInfo。有关 RealInfo 的详细信息，请参阅联机帮助。
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