Siemens SIWAREX WP251, Manual

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Communication with SIMATIC S7-1200
11.2 Communication via Modbus
SIWAREX WP251
Manual, 12/2015, A5E37203357A
195
11.2.4 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 179). The following tables list the Modbus registers used to
process these commands:
Table 11- 3 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
Table 11- 4 Command mailbox 2: Average priority
Variable Note Type Modbus registers
CMD2_CODE Code of command to be executed USHORT 920
CMD2_TRIGGER Trigger for starting the command USHORT 921
CMD2_STATUS 0=job running; 1=job finished (1 cycle) USHORT 922
CMD2_QUIT 0=no error; <>0=error code USHORT 923
Table 11- 5 Command mailbox 3: Low priority
Variable Note Type Modbus registers
CMD3_CODE Code of command to be executed USHORT 930
CMD3_TRIGGER Trigger for starting the command USHORT 931
CMD3_STATUS 0=job running; 1=job finished (1 cycle) USHORT 932
CMD3_QUIT 0=no error; <>0=error code USHORT 933
11.2.5 Reading registers
The method for reading registers depends on whether they belong to the writable data
records (DR 3 to DR 29) or can only be read as current values (DR 30 to DR 39).
If you wish to read the registers from the data records DR 3 to DR 29, you must first export
these as a complete data record to the internal output buffer.
All Modbus registers of the individual parameters can be found in chapter
→ Scale
parameters and functions (Page 57).