Detailed description   
2.12 Block descriptions 
  Power Line Basic PLC Program (P3) 
2-120  Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0 
2.12.4  FB 4: PI_SERV general PI services 
Description of functions 
FB PI_SERV can be used to start program-instance services in the NCK area. The possible 
services are described in this section. A program section, which carries out a particular 
function (e.g., with tool management, search for empty location in a magazine), is executed 
in the NCK by making a request via the PI service.  
Every FB 4 call must be assigned a separate instance DB from the user area. The multi-
instance capability can also be applied in SW 3.7 and higher. Please refer to the STEP 7 
Descriptions for more information.  
The specified service is referenced via the PIService parameter. The selected PI service is 
supplied via the freely assignable additional input variables with varying data types (Addr1 to 
Addr4 for strings, WVar1 to WVar 10 for integer or word variables). A job is started when FB 
4 is called by means of a positive edge change at control input Req. Successful execution of 
the job is displayed by means of a logic "1" in status parameter Done. Any errors are 
indicated by Error and State.  
The "PI" data block (DB16) contains internal descriptions of the possible PI services. A name 
must then be assigned to this DB in the signal list. On calling the FB 4, "DB-Name.PI-Name" 
is transferred as the actual parameter for PIService. 
The execution of the PI service extends over several PLC cycles (generally 1 to 2). The 
block can be called up in cyclic mode only. 
 
 
Note 
After communication between the PLC and NC (read/write NC variables, FB2, 3, 5, or PI 
general services, FB4) has been aborted by POWER OFF, the start jobs must be deleted in 
the first OB1 run after cold restart or reset (signal: Req = 0). 
FB 4 can start PI services only if the basic program parameter NCKomm has been set to "1" 
(in OB100: FB 1, DB7). 
 
Declaration 
 
FUNCTION_BLOCK FB 4 
VAR_INPUT 
  Req :  BOOL ; 
  PIService :  ANY ; 
  Unit :  INT ; 
  Addr1 :  ANY ; 
  Addr2 :  ANY ; 
  Addr3 :  ANY ; 
  Addr4 :  ANY ;