Eaton Electrical 1000 - Manual (Page 54)

MODBUS REGISTERS
EATON Power Xpert ® Gateway Series 1000 Card User’s Guide S 164201670 Rev 1 50
Modbus Register Addressing
This section describes Modbus function codes, data formats, and data
addressing.
Modbus Function Codes
The PDU/RPP registers are read using Modbus Function Codes (FC). For
most PDU/RPP registers, FC 04 is used. The PDU/RPP supports the
following hex function codes:
Table 1. Function Codes
FC Hex Description Use
01 0x01 Read Coil Status Supported for compatibility purposes
02 0x02 Read Discrete Inputs Single input data, such as alarms and
discrete contacts
03 0x03 Read Holding Registers Supported for compatibility purposes
04 0x04 Read Input Registers Analog data (most string and numeric
data types), such as voltage
05 0x05 Write Single Coil For future use
06 0x06 Write Single Register For future use
0F 0x0F Write Multiple Coils For future use
10 0x10 Write Multiple Registers For future use
Data Formats
Modbus programs usually provide an option for viewing various data
types. Refer to your Modbus program documentation for detailed
information on viewing data options.
A register is 16 bits (two bytes). The PDU/RPP supports the following
data types:
S
STRING – A string of ASCII characters (two per register). Consult the
Size parameter to find the string’s length for a given entry (it is a
multiple of two so that entries are register-aligned).
S
FLOAT – A 32-bit IEEE754 floating point number. FLOATs are always
two registers.
S
UINT – An unsigned integer. Consult the Size parameter to find the
integer’s size for a given entry (it is a multiple of two so that entries
are register-aligned).