FP_MC_PROTOCOL_READ

Read data from external devices via MC protocol

The PLC has the transmission right in the master communication. The communication is performed by sending commands to devices which support MC protocol and receiving responses. By specifying a memory address and executing a read instruction in a user program, the PLC generates a message according to the protocol automatically.

Parameters

Input

Port (WORD, INT, UINT)

Ethernet port e.g. SYS_ETHERNET_USER_CONNECTION_1

SourceMemoryArea (WORD, INT, UINT)

Memory area on the slave from where to request the data.

Unit	Memory area type	System variable
Bit	Input	X	Hexadecimal `SYS_MC_PROTOCOL_MEMORY_AREA_INPUT_X`
	Output	Y	Hexadecimal `SYS_MC_PROTOCOL_MEMORY_AREA_OUTPUT_Y`
	Link relay	B	Hexadecimal `SYS_MC_PROTOCOL_MEMORY_AREA_LINK_RELAY_B`
	Internal relay	M	Decimal `SYS_MC_PROTOCOL_MEMORY_AREA_INTERNAL_RELAY_M`
	Latch relay	L	Decimal `SYS_MC_PROTOCOL_MEMORY_AREA_LATCH_RELAY_L`
Word	Data register	D	Decimal `SYS_MC_PROTOCOL_MEMORY_AREA_DATA_REGISTER_D`
	File register	R	Decimal `SYS_MC_PROTOCOL_MEMORY_AREA_FILE_REGISTER_R`
	File register	ZR	Hexadecimal `SYS_MC_PROTOCOL_MEMORY_AREA_FILE_REGISTER_ZR`
	Link register	W	Hexadecimal `SYS_MC_PROTOCOL_MEMORY_AREA_LINK_REGISTER_W`

SourceMemoryOffset (DWORD, DINT, UDINT)

Offset of the memory area on the slave from where to request the data.

Range: 16#0–16#F7FFFF (0–16252927)

Words_Bits (WORD, INT, UINT)

Specify the number of received data. The number of received data is in word unit for the word transmission and in bit unit for the bit transmission (depending on the data type applied to the input Words_Bits)
The transfer method and the number of sent data specified by Words_Bits vary according to the data type of Destination.

Memory area specified in Destination	Transfer method	No. of sent data Words_Bits	Remarks
16-bit memory area WX, WY, WR, WL, DT, LD	Word transmission	1–960 words
1-bit memory area X,Y,R,L,DT,n,LD,n	Bit transmission	1–7168 bits	When the number of sent data is odd, 4-bit dummy code 16#0 is added.

Memory area specified in Destination

Transfer method

No. of sent data Words_Bits

Remarks

16-bit memory area

WX, WY, WR, WL, DT, LD

Word transmission

1–960 words

1-bit memory area

X,Y,R,L,DT,n,LD,n

Bit transmission

1–7168 bits

When the number of sent data is odd, 4-bit dummy code 16#0 is added.

Output

Destination (ANY)

Word area or register on the master unit to which the requested data is written.

Result (WORD, INT, UINT)

Specify the memory area of the master unit storing the execution result code (1 word in the area WX, WY, XR, WL, DT, LD)

0: Normal completion
1: Communication port is used for master communication
2: Communication port is used for slave communication
3: No. of master communication instructions that can be used at the same time is exceeded
4: Sending timeout
5: Response reception timeout
6: Received data error

Time chart

(1) Master communication clear-to-send flag,e.g. sys_bIsEthernetUserConnection1MasterCommunication
(2) Check that the master communication clear-to-send flag is TRUE and check that the master communication sending flag is FALSE
(3) Master communication sending flag, e.g. sys_bIsEthernetUserConnection1MasterCommunicationActive
While sending: Master communication sending flag is TRUE

Sending done: Master communication sending flag is FALSE
(4) Execute this instruction
(5) Master communication sending done flag, e.g. sys_bIsEthernetUserConnection1CommunicationError
Normal completion: FALSE

Abnormal completion: TRUE
(6) Send data
(7) Response reception processing

Error flags

sys_bIsOperationErrorHold (turns to TRUE and remains TRUE)

if the area specified using the index modifier exceeds the limit.
if a value specified for a parameter is outside the permissible range.
if Ethernet port is incorrect or Ethernet port is closed.
if the number of sent data specified by Words_Bits is incorrect.
if the word area or register on the master unit specified by Destination is incorrect or outside the permissible range.
if the memory area in which the execution result code is stored is incorrect.

sys_bIsOperationErrorNonHold (turns to TRUE for one scan)

if the area specified using the index modifier exceeds the limit.
if a value specified for a parameter is outside the permissible range.
if Ethernet port is incorrect or Ethernet port is closed.
if the number of sent data specified by Words_Bits is incorrect.
if the word area or register on the master unit specified by Destination is incorrect or outside the permissible range.
if the memory area in which the execution result code is stored is incorrect.

Example

POU header

All input and output variables used for programming this function have been declared in the POU header. The same POU header is used for all programming languages.

	VAR
		diMemoryOffset: DINT:=0;
		awValues: ARRAY [0..2] OF WORD:=[3(0)];
		iResult: INT:=0;
		bEnable: BOOL:=FALSE;
		abValues: ARRAY [0..2] OF BOOL:=[3(FALSE)];
		iPort: INT:=0;
	END_VAR

LD body

BODY
    WORKSPACE
        NETWORK_LIST_TYPE := NWTYPELD ;
        ACTIVE_NETWORK := 0 ;
    END_WORKSPACE
    NET_WORK
        NETWORK_TYPE := NWTYPELD ;
        NETWORK_LABEL :=  ;
        NETWORK_TITLE :=  ;
        NETWORK_HEIGHT := 6 ;
        NETWORK_BODY
B(B_COMMENT,,Bit transfer,2,0,10,1,);
B(B_COMMENT,,Memory Areas:	SYS_MC_PROTOCOL_MEMORY_AREA_INPUT_X ^SYS_MC_PROTOCOL_MEMORY_AREA_OUTPUT_Y ^SYS_MC_PROTOCOL_MEMORY_AREA_LINK_RELAY_B ^SYS_MC_PROTOCOL_MEMORY_AREA_INTERNAL_RELAY_M ^SYS_MC_PROTOCOL_MEMORY_AREA_LATCH_RELAY_L,13,0,39,6,);
L(1,0,1,6);
        END_NETWORK_BODY
    END_NET_WORK
    NET_WORK
        NETWORK_TYPE := NWTYPELD ;
        NETWORK_LABEL :=  ;
        NETWORK_TITLE :=  ;
        NETWORK_HEIGHT := 7 ;
        NETWORK_BODY
B(B_VARIN,,iPort,26,2,28,4,);
B(B_VAROUT,,abValues,41,2,43,4,);
B(B_VARIN,,SYS_MC_PROTOCOL_MEMORY_AREA_INPUT_X,26,3,28,5,);
B(B_VARIN,,diMemoryOffset,26,4,28,6,);
B(B_VAROUT,,iResult,41,3,43,5,);
B(B_CONTACT,,bEnable,5,1,7,3,);
B(B_F,FP_MC_PROTOCOL_READ!,,28,0,41,7,,?DEN?DPort?HSourceMemoryArea?DSourceMemoryOffset?DWords_Bits?AENO?CDestination?CResult);
B(B_F,Size_Of_Var!,,21,5,28,7,,?D?C);
B(B_VARIN,,abValues,19,5,21,7,);
L(7,2,28,2);
L(1,2,5,2);
L(1,0,1,7);
        END_NETWORK_BODY
    END_NET_WORK
    NET_WORK
        NETWORK_TYPE := NWTYPELD ;
        NETWORK_LABEL :=  ;
        NETWORK_TITLE :=  ;
        NETWORK_HEIGHT := 5 ;
        NETWORK_BODY
B(B_COMMENT,,Memory Areas:	 ^SYS_MC_PROTOCOL_MEMORY_AREA_DATA_REGISTER_D ^SYS_MC_PROTOCOL_MEMORY_AREA_FILE_REGISTER_R ^SYS_MC_PROTOCOL_MEMORY_AREA_FILE_REGISTER_ZR ^SYS_MC_PROTOCOL_MEMORY_AREA_LINK_REGISTER_W,13,0,39,5,);
B(B_COMMENT,,Word Transfer,2,0,10,1,);
L(1,0,1,5);
        END_NETWORK_BODY
    END_NET_WORK
    NET_WORK
        NETWORK_TYPE := NWTYPELD ;
        NETWORK_LABEL :=  ;
        NETWORK_TITLE :=  ;
        NETWORK_HEIGHT := 7 ;
        NETWORK_BODY
B(B_VARIN,,iPort,26,2,28,4,);
B(B_VAROUT,,awValues,41,2,43,4,);
B(B_VARIN,,SYS_MC_PROTOCOL_MEMORY_AREA_DATA_REGISTER_D,26,3,28,5,);
B(B_VARIN,,diMemoryOffset,26,4,28,6,);
B(B_VAROUT,,iResult,41,3,43,5,);
B(B_CONTACT,,bEnable,5,1,7,3,);
B(B_F,FP_MC_PROTOCOL_READ!,,28,0,41,7,,?DEN?DPort?HSourceMemoryArea?DSourceMemoryOffset?DWords_Bits?AENO?CDestination?CResult);
B(B_F,Size_Of_Var!,,21,5,28,7,,?D?C);
B(B_VARIN,,awValues,19,5,21,7,);
L(1,2,5,2);
L(7,2,28,2);
L(1,0,1,7);
        END_NETWORK_BODY
    END_NET_WORK
    NET_WORK
        NETWORK_TYPE := NWTYPELD ;
        NETWORK_LABEL :=  ;
        NETWORK_TITLE :=  ;
        NETWORK_HEIGHT := 5 ;
        NETWORK_BODY
B(B_COMMENT,,only valid for ethernet ports! ^--> Valid Ports:	SYS_ETHERNET_USER_CONNECTION_1 - SYS_ETHERNET_USER_CONNECTION_216,3,1,52,4,);
L(1,0,1,5);
        END_NETWORK_BODY
    END_NET_WORK
END_BODY

ST body

(*Bit transfer*)
If (bEnable) then
    FP_MC_PROTOCOL_READ(Port := iPort,
                        SourceMemoryArea := SYS_MC_PROTOCOL_MEMORY_AREA_INPUT_X,
                        SourceMemoryOffset := diMemoryOffset, 
                        Words_Bits := Size_Of_Var(abValues),
                        Destination => abValues, Result => iResult);
End_if;
(*Word transfer*)
If (bEnable) then
    FP_MC_PROTOCOL_READ(Port := iPort,
                        SourceMemoryArea := SYS_MC_PROTOCOL_MEMORY_AREA_DATA_REGISTER_D,
                        SourceMemoryOffset := diMemoryOffset, 
                        Words_Bits := Size_Of_Var(awValues),
                        Destination => awValues, Result => iResult);
End_if;