Siemens CP 1242-7 GPRS V2 - Page 101

Programming the program blocks
5.4 IF_CONF: SDT for the configuration data of the CP
CP 1242-7 GPRS V2
Operating Instructions, 10/2016, C79000-G8976-C311-02
101
1. Create a data block of the type "global DB" with block access "Standard".
2. Create a structure (data type "Struct") in the table of the parameter configuration of the
DB.
You can specify any name.
3. Under this structure add a header by assigning the name of the header and typing it in in
the cell of the data type "IF_CONF_Header".
The header of the structure and its three parameters (see below) is created.
4. Create a field for the first parameter to be changed by typing in the required data type (for
example "IF_CONF_APN") in the cell of the data type.
5. Repeat the last step for all parameters you want to change on the CP using the
TC_CONFIG instruction.
6. Finally, update the number of fields in the header in the "subfieldCnt" parameter.
Header of IF_CONF
Table 5- 1 IF_CONF_Header
Byte
Parameter
Data type
Initial value
Description
0 ... 1
fieldType
UINT
Field type: Must always be 0.
2 ... 3 fieldId UINT Field ID: Must always be 0.
4 ... 5
subfieldCnt
UINT
Total number of fields contained in the structure
General parameters of the parameter fields
Each field has the following general parameters:
● Id
This parameter identifies the field and must not be modified.
● Length
This parameter indicates the length of the field. The value serves as information.
Fields with strings and / or arrays have a variable length. Due to hidden bytes, the actual
length of fields can be greater than the sum of the displayed parameters.
● Mode
The following values are permitted to these parameters:
Table 5- 2 Values of "Mode"
Value
Meaning
1 Permanent validity of the configuration data
Not relevant for the CP
2 Temporary validity of the configuration data, including deleting of existing permanent
configuration data
The permanent configuration data is replaced by the parameter fields of IF_CONF.