Chapter 4 - 7SR120 · Data Communications Definitions
© 2017 Siemens Protection Devices Limited Chapter 4 - Page 31 of 84
Address Value
30002 2400
On reception these two registers should be interpreted in the correct order as IEEE754 floating point
representation.
4.2.2 FP_32BITS_3DP
The FP_32BITS_3DP is a 32 bit integer fixed point value, containing 3 decimal places of information. It is used
to send a real value to 3 decimal places as an integer. For example, if the value in a device is 123.456 it will
be sent as 123456. As it is an integer, negative numbers are sent as 2's complement.
FP_32BITS_3DP & MODBUS
In this MODBUS implementation the 32 bit value is stored in 2 16 registers in Big-Endian format. As
an example, if we take the hex representation of 123456, we have 1E240h. Assume this is stored in
the registers 30001 and 30002, it would look as follows:
Address Value
30001 1
30002 E240
On reception these two registers should be interpreted in the correct order as a 32 bit integer.
4.2.3 UINT32
The UINT32 is a signed 32 bit integer. As it is an integer, negative numbers are sent as 2's complement.
UINT32 & MODBUS
In this MODBUS implementation the 32 bit value is stored in 2 16 bit registers in Big-Endian format. As
an example, if we take the hex representation of -123456, in 2's complement, we have FFFE1DC0h.
Assume this is stored in the registers 30001 and 30002, it would look as follows:
Address Value
30001 FFFE
30002 1DC0
On reception these two registers should be interpreted in the correct order as a 32 bit integer.
4.2.4 UINT16
The UINT16 is a signed 16 bit integer. As it is an integer, negative numbers are sent as 2's complement.
UINT16 & MODBUS
In this MODBUS implementation the 16 bit value is stored in a 16 bit register in Big-Endian format. As
an example, if we take the hex representation of 5678 we have 162Eh. Assume this is stored in the
register 30001, it would look as follows:
Address Value
30001 162E
On reception this register should be interpreted as a 16 bit integer.
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