请问PQW外设输出字，PIB外设输入字是什么？
他们和QW IW的区别在哪里呀？
下面语句如何理解：
L： QW4
T PQW4


SFC 34 "QRY_DINT"的STATUS输出字是一个字，请问该字的具体含义，另外请问该字的低字节是否不用，而只用高字节存储STATUS信息 。
以下例子来自Programming with STEP 7 V5.1（6ES7 810-4CA05-8BA0）520页的
A.5.4 Example of Handling Time-Delay Interrupts
A.5.4.1 Structure of the User Program "Time-Delay Interrupts"

STL (OB1)
Network 1
L #STARTINFO.T_STMP.SECONDS
T MW 10
L #STARTINFO.T_STMP.MSEC_WDAY
T MW 12
L MD 10
SRD 4
T MD 10

Network 2:
A I 0.0
FP M 1.0
= M 1.1

Network 3:
A M 1.1
JNB m001
CALL SFC 32
OB_NO := 20
DTME := T#10S
SIGN := MW 12
RET_VAL:= MW 100
m001: NOP 0

Network 4:
CALL SFC 34 //Query status of time-delay interrupt(SFC QRY_DINT)
OB_NO := 20
RET_VAL:= MW 102
STATUS := MW 4 //此处把SFC 34的STATUS 赋值到MW4

Network 5:
A I 0.1
FP M 1.3
= M 1.4

Network 6: //...and time-delay interrupt is activated
A M 1.4 //(bit 2 of time-delay interrupt STATUS)? Then cancel time-delay interrupt
A M 5.2 //可为何在此处取用高字节？为何不取用M4.2呢？
JNB m002
CALL SFC 33
OB_NO := 20
RET_VAL:= MW 104
m002: NOP 0
A I 0.2
R Q 4.0