看这里：
SUBROUTINE_BLOCK CRC8:SBR1
TITLE=子例行程序注释
VAR_INPUT
输入:DWORD;
END_VAR
VAR
计数器1:WORD;
计数器2:WORD;
计数器3:WORD;
计数器4:WORD;
变量1:BYTE;
变量2:BYTE;
变量3:BYTE;
END_VAR
BEGIN
Network 1
LD SM0.0
MOVB *LD0, LB12
Network 2
LD SM0.0
FOR LW6, +0, +7
Network 3
LD SM0.0
MOVB LB12, LB13
ANDB 16#80, LB13
Network 4
LDB= LB13, 0
SLB LB12, 1
Network 5
LDB<> LB13, 0
SLB LB12, 1
AENO
XORB 16#07, LB12
Network 6
NEXT
Network 7
// 从0到3，对指针加四次。因为计算的是五个字节的CRC。
LD SM0.0
FOR LW8, +0, +3
Network 8
// 对指针再加一，把CRC存入第六个字节。
LD SM0.0
INCD LD0
AENO
MOVB *LD0, LB14
AENO
XORB LB14, LB12
Network 9
LD SM0.0
FOR LW10, +0, +7
Network 10
LD SM0.0
MOVB LB12, LB13
ANDB 16#80, LB13
Network 11
LDB= LB13, 0
SLB LB12, 1
Network 12
LDB<> LB13, 0
SLB LB12, 1
AENO
XORB 16#07, LB12
Network 13
NEXT
Network 14
NEXT
Network 15 // Network Title
// Network Comment
LD SM0.0
INCD LD0
AENO
MOVB LB12, *LD0
INVB *LD0
Network 16


Network 17 // 网络标题
// 网络注释
END_SUBROUTINE_BLOCK