Application Examples

Description

The following program is a short demo application with four instances of XXMIT showing the four main functions:

Modbus Master
Simple ASCII In
ASCII Message Out
Terminated ASCII In

Modbus Master

The following Modbus Master operation is a read request to a slave (address 4 for example) device connected to port 1 of the master:

Read slave's %MW1 to %MW10
into local %MW11 to %MW20

The Slave (address 4) must be set up with the following port parameters:

9600 baud
8 data bits
1 stop bit
even parity (2)

The Master uses settings from XXMIT

Variable declaration for Modbus Master

The following table shows the variables used in the Modbus Master example:

Variable Name	Data Type	Initial Value	Comment
StartModbusMstr	BOOL
ModbusMstrActive	BOOL
ModbusMstrCommand	WORD	16#0100	Bit 8 set
ModbusMstrDone	BOOL
ModbusMstrError	BOOL
ModbusMstrSettings	WordArr9
ModbusMstrSettings[1]		3	Modbus Code: Read multiple words
ModbusMstrSettings[2]		10	Amount of Words to read
ModbusMstrSettings[3]		4	Slave Modbus address
ModbusMstrSettings[4]		1	Source word
ModbusMstrSettings[5]		11	Destination Word
ModbusMstrSettings[6]		0	not used
ModbusMstrSettings[7]			not used
ModbusMstrSettings[8]			not used
ModbusMstrSettings[9]			not used
ModbusMstrStatus	INT
ModbusMstrNode	WORD	4	Enter Slave address
ModbusMstrErrorCounter	INT
ModbusMstrDoneCounter	INT

IEC Section for Modbus Master

Program the following in an FBD section:

Simple ASCII Receive

Receives whatever comes into port 1. The receive buffer's length is assigned as 'SimpleReceiveLength', which has an initial value of 10.

Received characters are in MsgIn array, number of received characters in RecCount.

Variable declaration for Simple ASCII Receive

The following table shows the variables used in the Simple ASCII Receive example:

Variable Name	Data Type	Initial Value	Comment
StartSimpleReceive	BOOL
SimpleReceiveActive	BOOL
SimpleReceiveCharCounter	INT
SimpleReceiveCommand	WORD	16#0480	Bits 7 and 10 set. FIFO enabled
SimpleReceiveDone	BOOL
SimpleReceiveError	BOOL
SimpleReceiveLength	INT	10
SimpleReceiveRetryCounter	INT
SimpleReceiveStatus	INT
SimpleRecMessage	ByteArr12
SimpleReceiveDoneCounter	INT
SimpleReceiveErrorCounter	INT

IEC Section for Simple ASCII Receive

Simple ASCII Send

Sends a simple ASCII message out off port 1, the message is 'Hello World!!'

Variable declaration for Simple ASCII Send

The following table shows the variables used in the Simple ASCII Send example:

Variable Name	Data Type	Initial Value	Comment
StartSimpleSend	BOOL
SimpleSendActive	BOOL
SimpleSendCommand	WORD	16#0200	Bit 9 set
SimpleSendDone	BOOL
SimpleSendError	BOOL
SimpleSendLength	INT	14	Number of characters to send
SimpleSendMessage SimpleSendMessage[1] SimpleSendMessage[2] SimpleSendMessage[3] SimpleSendMessage[4] SimpleSendMessage[5] SimpleSendMessage[6] SimpleSendMessage[7] SimpleSendMessage[8] SimpleSendMessage[9] SimpleSendMessage[10] SimpleSendMessage[11] SimpleSendMessage[12] SimpleSendMessage[13] SimpleSendMessage[14]	ByteArr36	16#48 16#65 16#6C 16#6C 16#6F 16#20 16#57 16#6F 16#72 16#6C 16#64 16#20 16#21 16#21	'Hello World !!'
SimpleSendRetryCounter	INT
SimpleSendStatus	INT
SimpleSendDoneCounter	INT
SimpleSendErrorCounter	INT

IEC Section for Simple ASCII Send

Terminated ASCII Receive

After receiving the 'starting characters' "AB", the function block puts all received characters into the receive buffer MsgIn. The receiver will stop when the 'finishing characters' "CD" are received, whereby the "Done" output will be set, to indicate the successfull completion. The max. length of the receive buffer is assigned as "TermReceiveLength", which is set to an initial value of 20 in this example.

Variable declaration for Terminated ASCII Receive

The following table shows the variables used in the Terminated ASCII Receive example:

Variable Name	Data Type	Initial Value	Comment
StartTermReceive	BOOL
TermReceiveActive	BOOL
TermReceiveCharCounter	INT
TermReceiveCommand	WORD	16#0880	Bits 11 and 7 set. FIFO enabled
TermReceiveDone	BOOL
TermReceiveError	BOOL
TermReceiveLength	INT	20
TermReceiveMessage	ByteArr36		Received characters
TermReceiveRetryCounter	INT
TermReceiveSettings TermReceiveSettings[1] TermReceiveSettings[2] TermReceiveSettings[3] TermReceiveSettings[4] TermReceiveSettings[5] TermReceiveSettings[6]	ByteArr36	16#02 16#02 16#41 16#42 16#43 16#44	length of termination string (1 or 2) length of start string (0, 1 or 2) 1st start character 2nd start character 1st termination character 2nd termination character
TermReceiveStatus	INT
TermReceiveDoneCounter	INT
TermReceiveErrorCounter	INT

IEC Section for Terminated ASCII Receive

Entering Strings as initial values

The Data Editor of Control Expert allows you to easily enter Strings as initial values into byte arrays.

The following part gives a short describtion of how to define a variable 'DemoString' as 'ByteArr36' and enter a string 'My Text ! ' as initial value.

Open the Data Editor

From the main menu select:

Tools -> Data Editor.

Declaring new String name

Declare stringname for Array by clicking on next to type (in this case bool) This will then open a variable type selection window.

Define Element Type

Check the Array checkbox and define array element type and number of elements. It is now possible to see and modify values for expanded byteArr36.