Siemens SIMATIC S7 System Manual page 507

Example
This is an example usage of the ISO_CONNECT instruction:
STEP7-Micro/WIN SMART always uses pointers to pass a string to the ISO_CONNECT
instruction for the RemTsap and the LocTsap. If you use a constant string (as in the example
above), STEP7-Micro/WIN SMART automatically creates the string and the pointer. If you
wish to create strings in a Data Block and then pass a pointer to one of these strings, you
would follow these steps:
1. In the Data Block, create the strings:
– VB100 "machine_1"
– VB120 "machine_2"
2. Use "&VB100" or "&VB120" (without the quote marks) for the TSAP parameters on the
ISO_CONNECT instruction.
S7-200 SMART
System Manual, V2.3, 07/2017, A5E03822230-AF
9.4 Open user communication library
Libraries
507