此系统常量是当前所选PLC类型的唯一值。允许仅针对当前所选PLC类型编译程序。
#if((SYS_CURRENT_PLC AND (SYS_FP0 OR SYS_FP_e))<>0) #then
(* only code for FP0 or FPe is executed*)
#elsif ((SYS_CURRENT_PLC AND (SYS_FP2 OR SYS_FP2SH OR SYS_FP10SH))<>0) #then
(* only code for FP2,FP2SH or FP10SH is executed*)
#end_if;