Siemens bt300 Operator's Manual page 140

Chapter 4 - Parameters and Menu Structure
I/O and Hardware (M5)
Slave device failure (P5.8.3.2.8)
An unrecoverable error occurred while the server (or slave) was attempting to perform the requested action.
Last fault response (P5.8.3.2.9)
Displays the last fault response as Fault code.
Control word (P5.8.3.2.10)
Displays the Control Word received from the bus.
Word status (P5.8.3.2.11)
Displays the current Status Word that is sent to the bus.
Communications
Features of the Modbus-Siemens interface:
● Direct control of the Siemens drive (for example, Run, Stop, Direction, Speed reference, Fault reset)
● Full access to all Siemens parameters
● Monitor the Siemens status (Output frequency, Output current, Fault code)
Data addresses in Modbus messages
All data addresses in Modbus messages are referenced to zero. The first occurrence of a data item is addressed
as item number zero. For example:
● The coil known as Coil 1 in a programmable controller is addressed as Coil 0000 in the data address field of a
Modbus message.
● Coil 127 decimal is addressed as Coil 007E hex (126 decimal).
● Holding register 40001 is addressed as register 0000 in the data address field of the message. The function
code field already specifies a 'holding register' operation. Therefore the 4XXXX reference is implicit.
● Holding register 40108 is addressed as register 006B hex (107 decimal).
Modbus Memory Map
The Siemens variables and fault codes as well as the parameters can be read and written from Modbus. The
parameter addresses are determined in the application. Every parameter and actual value has been given an ID
number in the application. The ID numbering of the parameter as well as the parameter ranges and steps can be
found in the operator's manual in question. The parameter value shall be given without decimals. If several
parameters/actual values are read with one message, the addresses of the parameters/actual values must be
consecutive.
Function
Code
1 (0X01) Read coils
2 (0X02) Read Discrete Inputs
3 (0X03) Read Holding Registers
4 (0X04) Read Input Registers
5 (0X05) Write Single Coils
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Siemens Industry, Inc.
Building Technologies
Table 109: Supported Modbus Functions.
Modbus Function Name
Siemens BT300 HVAC Drive
TCP/RTU Access Type Address Range (hex)
TCP only Discrete
TCP only Discrete
TCP&RTU 16bit
TCP&RTU 16bit
TCP only Discrete
00000 - 0FFFF
10000 - 1FFFF
40000 - 4FFFF
30000 - 3FFFF
00000 - 0FFFF
DPD01809
2016-06-07