Command code = 2000 + X (X = desired data record number)
The following equation for generation of a corresponding command code applies to the writing
of data records from the data block to the SIWAREX:
Command code = 4000 + X (X = desired data record number)
Example
The following example clarifies the actions with command mailboxes and data records:
"Calibration weight" is to be set to a value of 60.5 by the CPU. Since "Calibration weight" is a
parameter of data record 3 (see chapter → Scale parameters and functions (Page 59)), service
mode must first be activated. This is possible using command code "1" (see chapter →
Command lists (Page 101)).
The variable "i_CMD_CODE" must therefore be assigned the value "1" and the associated
"bo_CMD_TRIGGER" set to TRUE. Subsequently, the module is directly in service mode
(DIAG LED flashes green):
i_CMD_CODE = 1
bo_CMD_TRIGGER = TRUE
Since only complete data records can be read or written, it is recommendable to now read data
record 3 into the CPU. This is carried out using command code 2003 (see chapter → Command
lists (Page 101)):
i_CMD_CODE = 2003
bo_CMD_TRIGGER = TRUE
All current data from data record 3 are now present in the data block. The calibration weight is
then set as desired to a value of 60.5:
CALIBRATION_WEIGHT = 60.5
The modified data record 3 must now be written into the SIWAREX again. This is carried out
using command code 4003 (see chapter → Command lists (Page 101)):
i_CMD_CODE = 4003
bo_CMD_TRIGGER = TRUE
The new calibration weight is now present in the SIWAREX and can be used. Service mode for
the module should subsequently be switched off again using the command "2".
This procedure for reading and writing data records or parameters is identical for all data
records.
Communication in SIMATIC S7-300/400/1200/1500
11.6 Working with the function block
SIWAREX WP321
Operating Instructions, 08/2019, A5E33715669A-AD 109
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