Modbustcp Slave Error Answer (Bk9000, Bx/Bc9Xx0, Ip/Ilxxxx-B/C900, Ek9000); Modbustcp Functions - Beckhoff BC9000 Documentation

7.5.3 ModbusTCP slave error answer (BK9000, BX/BC9xx0, IP/
ILxxxx-B/C900, EK9000)
When the user sends the slave either a request or information that the coupler does not understand, the
slave responds with an error report. This answer contains the function and the error code. 0x80 is added to
the value returned by the function.
Code Name
1 ILLEGAL FUNCTION
2 ILLEGAL DATA ADDRESS Invalid address or length
3 ILLEGAL DATA VALUE
4 SLAVE DEVICE ERROR
6 SLAVE DEVICE BUSY
7.5.4

ModbusTCP functions

7.5.4.1 ModbusTCP functions
In the Modbus protocol, the functions determine whether data is to be read or written, and what kind of data
is involved.
Function
Read coil status [} 67]
Read input status [} 68]
Read holding register [} 68]
Read input register [} 69]
Force single coil [} 70]
Preset single register [} 70]
Diagnostics [} 71]
Force multiple coils [} 72]
Preset multiple register [} 73]
Read / write registers [} 73]
GPR (General Preset Register) - register structure of the Modbus interface (see appendix)
7.5.4.2 Read coil status (Function 1)
The Read coil status function can be used to read the digital outputs that have been set.
The first 10 digital outputs are read in this example. The start address is zero. An offset can be entered in the
Start address field
BC9000 and BC9100
Meaning
Modbus function not implemented
Invalid parameter
- Diagnostic functions
- Incorrect register
Watchdog or K-bus error
EK9000: E-bus error
Output data is already been received from another IP device
Code Description
1 Read digital outputs
2 Read digital inputs
3 Read analog outputs and inputs / GPR
4 Reading the inputs / GPR
5 Writing a digital output
6 Writing an output / GPR
8 Diagnostics
15 Write a number of digital outputs
16 Writing several outputs / GPRs
23 Write and read a number of process data outputs / GPRs
Version: 4.0.0
Fieldbus system
67