HMS Anybus Modbus to KNX Gateway User Manual page 10

Product Description
3.4.1 Modbus Points Definition
Each point defined in the gateway has the following Modbus features associated to it:
Feature
Modbus Device
Function code
Read Func
Write Func
#Bits
Data Coding Format
Byte Order
Register Address
Bit inside the register
Modbus to KNX Gateway User Manual
Description
Modbus TCP device to which belongs the point, from a list of Modbus TCP slave devices
that can be defined in the gateway (up to 5).
For every Modbus TCP slave device defined, a virtual signal is created automatically in
the gateway to inform about the communication with the device, this signal is available
also from the KNX interface like the rest of the points.
One of the following Modbus function codes can be used:
• 1- Read Coils.
• 2- Read Discrete Inputs.
• 3- Read Holding Registers.
• 4- Read Input Registers.
• 5- Write Single Coil.
• 6- Write Single Register.
• 15- Write Multiple Coils.
• 16- Write Multiple Registers.
Number of bits to be used by this signal.
One of the following Modbus data coding formats can be used:
• 16/32/48/64 bits unsigned.
• 16/32/48/64 bits signed (one's complement – C1).
• 16/32/48/64 bits signed (two's complement – C2).
• 16/32/48/64 bits Float.
• 16/32/48/64 bits Bitfields.
• Error comm
• Big Endian
• Little Endian
• Word Inverted Big Endian
• Word Inverted Little Endian
The Modbus register address inside the slave device for the point.
Bit inside the Modbus register (optional). The gateway allows bit decoding from generic
16 bits input/holding Modbus registers.
Bit coding into 16 bit input/holding Modbus registers is used for some devices to encode
digital values into this type of registers, being these registers normally accessible using
Modbus function codes 3 and 4 (read holding/input registers).
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SCM-1202-050 1.2 en-US