F115_FIFT

FIFO缓冲区定义

F115指定FIFO（先入先出）缓冲区的开始区域d1_Start和FIFO缓冲区的存储容量n_Number。

参数

输入

n_Number (INT)

指定FIFO缓冲区的存储容量

范围：1-256

d1_Start (WORD, INT, UINT)

FIFO缓冲区的开始16位区域

标注

建议使用相应的FP7指令，来代替使用此F型指令：FP_FIFO_DEFINE, FP_LIFO_DEFINE
在FIFO缓冲区写入或读取之前，只能执行一次使用FIFT指令定义区域。当执行FIFT指令时，FIFO缓冲区定义如下：
1. (1) FIFO缓冲区的存储容量（n）
2. (2) 存储数据项的数量（字），已写入且未读取
3. (3) FIFO指针
4. (4) 数据存储区域（n个字）
5. (5) 写入指针 (0–255/16#00–16#FF)
6. (6) 读取指针 (0–255/16#00–16#FF)
当执行FIFT指令时，以下内容存储为默认值：d1_Start = n_Number (由FIFT指令指定的值）、d1_Start + 1 = 0和d1_Start + 2 = 16#0000.

错误标志

sys_bIsOperationErrorHold（变为TRUE并保持为TRUE）

如果n_Number = 0
如果n_Number > 256
如果由n_Number指定的区域超出限制

sys_bIsOperationErrorNonHold（对于一次扫描变为TRUE）

如果n_Number = 0
如果n_Number > 256
如果由n_Number指定的区域超出限制

示例

DUT

此示例通过合并函数F115_FIFT、F116_FIFR和F117_FIFW来说明FIFO缓冲区。

POU头

所有用于编程此函数的输入和输出变量已在POU头中声明。所有编程语言使用相同的POU头。

VAR
		FIFO: FIFO_n_WORD;
		iRead_Data: INT:=0;
		iWrite_Data: INT:=1;
		bFIFO_Initialize: BOOL:=FALSE;
		bFIFO_Write: BOOL:=FALSE;
		bFIFO_Read: BOOL:=FALSE;
		bChange_Value: BOOL:=FALSE;
	END_VAR

POU本体

以下示例说明在bFIFO_Write启用两次和bFIFO_Read启用一次后的缓冲区状态。当首次激活bFIFO_Write时，FIFO.awData[0]中写入数值1。当启用bFIFO_Read时，iRead_Data就会读取此值。当第二次启用bFIFO_Write时，写入指针递增2且FIFO.awData[1]中写入数值1。参见执行数据监控1

LD本体

BODY
    WORKSPACE
        NETWORK_LIST_TYPE := NWTYPELD ;
    END_WORKSPACE
    NET_WORK
        NETWORK_TYPE := NWTYPELD ;
        NETWORK_LABEL :=  ;
        NETWORK_TITLE :=  ;
        NETWORK_HEIGHT := 7 ;
        NETWORK_BODY
B(B_CONTACT,,bFIFO_Initialize,6,1,8,3,R);
B(B_F,F115_FIFT,,24,0,33,5,,?DEN?Dn?Dd1?AENO);
B(B_VARIN,,FIFO.awData,11,3,13,5,);
B(B_F,Size_Of_Var,,13,2,23,5,,?D@'Var'?CSize);
B(B_VARIN,,FIFO.iSize,11,5,13,7,);
L(1,0,1,7);
L(1,2,6,2);
L(8,2,24,2);
L(23,3,24,3);
L(23,3,23,4);
L(24,4,24,6);
L(13,6,24,6);
        END_NETWORK_BODY
    END_NET_WORK
    NET_WORK
        NETWORK_TYPE := NWTYPELD ;
        NETWORK_LABEL :=  ;
        NETWORK_TITLE :=  ;
        NETWORK_HEIGHT := 9 ;
        NETWORK_BODY
B(B_COMMENT,,The LT (Lower Than) operator prevents a writing error from occurring.,3,1,33,2,);
B(B_VARIN,,FIFO.iNumber,8,4,10,6,);
B(B_F,@LT-2,,10,3,15,7,,?D?D?C);
B(B_CONTACT,,bFIFO_Write,17,4,19,6,R);
B(B_VARIN,,FIFO.iSize,8,5,10,7,);
B(B_F,F117_FIFW,,24,4,33,8,,?DEN?D@'s'?AENO?Cd1);
B(B_VARIN,,iWrite_Data,22,6,24,8,);
B(B_VAROUT,,FIFO.iSize,33,6,35,8,);
L(1,0,1,9);
L(15,5,17,5);
L(19,5,19,6);
L(19,6,24,6);
        END_NETWORK_BODY
    END_NET_WORK
    NET_WORK
        NETWORK_TYPE := NWTYPELD ;
        NETWORK_LABEL :=  ;
        NETWORK_TITLE :=  ;
        NETWORK_HEIGHT := 9 ;
        NETWORK_BODY
B(B_COMMENT,,The GT (Greater Than) operator prevents a reading error from occurring.,3,1,34,2,);
B(B_VARIN,,FIFO.iNumber,7,4,9,6,);
B(B_F,@GT-2,,9,3,14,7,,?D?D?C);
B(B_CONTACT,,bFIFO_Read,16,4,18,6,R);
B(B_VARIN,,0,7,5,9,7,);
B(B_F,F116_FIFR,,24,4,33,8,,?DEN?Dd1?AENO?Cd2);
B(B_VARIN,,FIFO.iSize,22,6,24,8,);
B(B_VAROUT,,iRead_Data,33,6,35,8,);
L(1,0,1,9);
L(14,5,16,5);
L(18,5,18,6);
L(18,6,24,6);
        END_NETWORK_BODY
    END_NET_WORK
    NET_WORK
        NETWORK_TYPE := NWTYPELD ;
        NETWORK_LABEL :=  ;
        NETWORK_TITLE :=  ;
        NETWORK_HEIGHT := 9 ;
        NETWORK_BODY
B(B_COMMENT,,The E_ADD function is for cosmetic purposes only. It increments the value for the variable iWrite_Data~ which you can more easily differentiate when it is written into the Array of the FIFO buffer.,3,1,34,4,);
B(B_CONTACT,,bChange_Value,9,5,11,7,R);
B(B_F,E_ADD-2,,22,4,28,9,,?DEN?Da_NumN?Da_NumN?AENO?C);
B(B_VARIN,,iWrite_Data,20,6,22,8,);
B(B_VAROUT,,iWrite_Data,28,6,30,8,);
B(B_VARIN,,1,20,7,22,9,);
L(1,0,1,9);
L(1,6,9,6);
L(11,6,22,6);
        END_NETWORK_BODY
    END_NET_WORK
END_BODY

ST本体

IF DF(bFIFO_Initialize) THEN
	(* Create the FIFO buffer *)
	F115_FIFT(n_Number := Size_Of_Var(FIFO.awData), d1_Start :=  FIFO.iSize);
	REPEAT
		(* Initialize FIFO buffer with values *)
		iWrite_Data:=iWrite_Data+1;
		F117_FIFW(s := iWrite_Data, d1_Start => FIFO.iSize);
	UNTIL(FIFO.iNumber>=FIFO.iSize)
	END_REPEAT;
END_IF;

IF DF( bFIFO_Write) THEN
	(* Write value of Write_Data to FIFO buffer *)
	(* at leading edge of FIFO_Write *)
	F117_FIFW(s := iWrite_Data, d1_Start => FIFO.iSize);
END_IF;

IF DF(bFIFO_Read) THEN
	(* Read value from FIFO buffer *)
	(* at leading edge of FIFO_Read *)
	F116_FIFR(d1_Start := FIFO.iSize, d2 => iRead_Data);
END_IF;