子程序FB1中的变量声明：
IN:
PROCESS_INPUT
PRES_H_ALARMSET
PRES_HH_ALARMSET
TEMP_H_ALARMSET
TEMP_HH_ALARMSET
T_NO1
T_NO2
OUT:
PRES_H_ALARM
TEMP_H_ALARM
PRES_HH_ALARM
TEMP_HH_ALARM
PRES_HH_LOCK_DELAY
TEMP_HH_LOCK_DELAY

FB1中的程序：

A(
L #PROCESS_INPUT
L #PRES_H_ALARMSET
>=R
)
A(
L #PROCESS_INPUT
L #PRES_HH_ALARMSET
)
= #PRES_H_ALARM
A(
L #PROCESS_INPUT
L #TEMP_H_ALARMSET
>=R
)
A(
L #PROCESS_INPUT
L #TEMP_HH_ALARMSET
)
= #TEMP_H_ALARM
L #PROCESS_INPUT
L #PRES_HH_ALARMSET
>=R
= #PRES_HH_ALARM
L #PROCESS_INPUT
L #TEMP_HH_ALARMSET
>=R
= #TEMP_HH_ALARM
A #PRES_HH_ALARM
L S5T#5S
SD #T_NO1
NOP 0
NOP 0
NOP 0
A #T_NO1
= #PRES_HH_LOCK_DELAY
A #TEMP_HH_ALARM
L S5T#5S
SD #T_NO2
NOP 0
NOP 0
NOP 0
A #T_NO2
= #TEMP_HH_LOCK_DELAY
实际上就是压力和温度的HA，HHA和HHA延时后联锁输出。