Maple Systems OIT Family - Manual (Page 54)

Floating Point
(OIT3100 and OIT4100 Series Only)
This format is used to represent a 32-bit register in the PLC as a Floating Point value.
The Floating Point format is based on the IEEE 754 Basic Single Precision Floating Point
specification:
Number of Bits [bit location]
sign exponent mantissa
1 [31] 8 [30-23] 23 [22-0]
IEEE 754 Single Precision
Due to limitations in the OIT, the implementation of floating point in the OIT is a subset
of the IEEE 754 specification. The Decimal Point location determines the range of the
Floating Point value:
Decimal Range
Location Minimum Maximum
0 - 2,147,483,647 + 2,147,483,647
1 - 214,748,364.7 + 214,748,364.7
2 - 21,474,836.47 + 21,474,836.47
3 - 2.147.483.647 + 2,147,483.647
4 - 214,748.3647 + 214,748.3647
5 - 21,474.83647 + 21,474.83647
6 - 2,147.483647 + 2,147.483647
7 - 214.7483647 + 214.7483647
8 - 21.47483647 + 21.47483647
9 - 2.147483647 + 2.147483647
10 - 0.2147483647 + 0.2147483647
Accuracy
Due to limitations of the OIT, the Floating Point format is accurate to 6 digits. This
means that values in the seventh and higher digits may not be correct.
For example, if the OIT displays a value of
+ 12345.678, only the value 12345.6 is
reliable. The remaining digits are displayed, but may not be accurate.
If the OIT displays a value of
+ 2,147,483,647, then only the digits up to the “8” are
reliable. The remaining digits are displayed, but may not be accurate.
Out-of-Range Conditions:
NOTE: In the examples below, commas are shown for clarity. The OIT will display commas
only if the Commas checkbox in the Special Effects area is checked.
Any value read from the PLC that is outside the range specified above will be displayed
as ########. See Example 1.
Example 1, Out Of Range Value (Overflow/Underflow)
PLC Register contains: -214,100.45
Decimal Location: 5 ( 21,474.83647 to + 21,474.83647)
OIT Displays: ########
PLC Register Monitors 54
1010-0099, Rev. 07