Communication
11.2 Communication via Modbus
SIWAREX WP231
154
Manual, 07/2014, A5E31238908A-02
The following baud rates can be set:
●
9 600 bit/s
●
19 200 bit/s (default setting)
●
38 400 bit/s
●
57 600 bit/s
●
115 000 bit/s
Functions which can be used by the master are listed below. The structure and contents of
the registers are shown in chapter "Scale parameters and functions (Page 63)".
Service
Function code
Usage
Read Holding Registers
03
Read one or more 16-bit parameter registers
Write Single Register
06
Write a single parameter register
Write Multiple Registers
16
Write multiple registers
If a request of the master is answered by the SIWAREX module (slave), the SIWAREX
module sends a response frame with or without errors. In the case of a response without
error message, the response frame contains the received function code; in the case of
errors, the highest bit of the function code is set. This corresponds to the Modbus standard.
Afterwards, the master requests the data record DR 32 to check which process-related data
or operator errors exist.
11.2.1.2
Data record concept
The register assignment is an image of the data records. The chapter →
and functions (Page 63) describes the data records, variables and functions, including the
register addresses. The data records are always checked as complete data packets for
plausibility. For this reason, you must follow a specific procedure to change individual
parameters.
11.2.1.3
Command mailboxes
Corresponding command codes must be sent in order to execute commands and to read
and write data records in the Modbus buffer memories. These are described in more detail in
chapter →
Command lists (Page 139). The following tables list the Modbus registers used to
process these commands:
Table 11- 4 Command mailbox 1: Highest priority
Variable
Note
Type
Modbus registers
CMD1_CODE
Code of command to be executed
USHORT
910
CMD1_TRIGGER
Trigger for starting the command
USHORT
911
CMD1_STATUS
0=job running; 1=job finished (1 cycle)
USHORT
912
CMD1_QUIT
0=no error; <>0=error code
USHORT
913
Summary of Contents for SIWAREX WP231
Page 16: ...Safety notes 2 1 General safety instructions SIWAREX WP231 16 Manual 07 2014 A5E31238908A 02 ...
Page 132: ......
Page 174: ...Technical data 13 3 Approvals SIWAREX WP231 174 Manual 07 2014 A5E31238908A 02 ...
Page 180: ...List of abbreviations SIWAREX WP231 180 Manual 07 2014 A5E31238908A 02 ...
Page 182: ...Index SIWAREX WP231 182 Manual 07 2014 A5E31238908A 02 ...