Because of S7-300/400 MPI Networks connected to PC over Com port, maximum connected PLC count is specified by PC's Com port count. Com port count can be increased by USB-Serial converters. Can not connect to one PLC from two different Networks.
In Properties window;
PC Serial Port, determines the serial port that used for Network connection.
PC Baudrate, determines the Baudrate of the RS 232 connection between PC and MPI adapter. PC Baudrate can be determined as 115200 for some MPI adapters.
MPI Baudrate, determines the Baudrate of the RS 485 connection between MPI adapter and PLC.
PC MPI Address, a PC should have an address in the MPI network. This field used for determining this address.
Poll Interval, determines period of queries that send to PLC. This value ignored while writing data to PLC. Value is written to PLC immediately at the time of the command executed.
Groups that created in the station and Tags that belong to group
In Tag list, Rows can be selected by clicking on left side title of the Row. Multiple Rows can be selected by pressing Ctrl key while selecting rows or dragging the mouse.
Selected rows can be deleted by pressing Delete key on the keyboard or selecting Delete command from the right click menu on the related row.
Grup Menu:
When right click on Group, Group Menu opens which allows group related operations.
Cycle, determines group's read period.
All Tags will be listed when Station selected.
When Network selected the Tags listed which belongs to last selected group or station
Delete, deletes the group.
First information in this group is Tag Count.
Good is the number of successul communication since Network has been activated.
Bad indicates failed communication count.
Query Byte Count: Most important information of this group. Query is calculated according to entered variable addresses. Then it is sent to PLC. According to calculated query, the byte count that PLC should sent is shown here.
WinTr tries to read all Tags in the group at once. If entered addresses are sequental, all list read at once. In WinTr, maximum 222 byte can be read at once for S7-300/400 MPI standart. Calculated query size is shown as the Query Byte Count in the Statusstrip. If you see different count than you estimated, there could be an error.
Adjusting Query Byte Count for Best Performance:
Query Byte Count should be maximum to get high performance. For example we have 13 byte data communication in our Network. Communication performance will be change according addresses to be read .
If 13 byte is reached sequentally, communication performance will be maximum. In this case Query Byte Count will indicate 13.
Disconnecting the Network
If same bytes are reached repeatedly, this will cause negative effect on communication performance.
Tag Name Column: Each newly created Tag will be named with a unique name. This name can be changed by user with another unique name.
Value Type Column: Siemens S7 PLC's data types selected from this column. All types read and transferred to PLC in S7 format. But they are displayed in Windows standart.
Displayed Data Types:
S7-300/400 PLC's Input, Output, Marker and Datablok registers can be read and written by WinTr.
Address information specifies data size. For example M 0.0 is one bit size, MD 8 is 4 byte size. Suitable value types determined according to address that entered in this field.
Register addresses can be typed without a space. For example mw8 will be recognized as MW 8.
Tag List:
The list at the right side which contains created tags.
When right clicked on Network, a menu opens which contains Network and Station groups.
Sample application scheme
Network Menu - Network Group:
Network group made up by two item as Properties and Delete.
Properties, displays Properties window which contains Network settings.
Network menu Network group
Network Menu - Station Group:
The commands in this menu are disabled.
Delete command in the Network menu Deletes the Network.
When right clicked on the station, a menu opens which contains Station and Group groups.
Station Menu - Station Group:
In this group;
Address, determines address of the group that will connect.
Station Menu - Group Group:
This menu contains only Add command which creates a new group.
Station Menu - Station Group
Station Menu - Adding a group
Name, determines group's name.
Notifying PLC Tags that can not be accessed
Deleting a Network:
A menu opens when right clicked on the Network. Selecting Delete will delete the Network.
Additionally, Network can be deleted from the Network Menu as described at bottom.
S7-300/400 MPI module located in the Connection Manager and used for communicating Siemens S7-300 and S7-400 devices using MPI standart.
When right mouse button clicked in the white area at the left, a menu opens. A new Network is created by clicking Add in this menu.
Tag values will be read from PLC adresses and shown in the Read Value column in both connection types.
The PLC variables that can not be accessed for any reason will be notified with the red background.
To write a PLC, value must be entered to related row's Write Value column then pressed Enter key on the keyboard.
Groups:
Tags are created in Groups.
Maximum 128 group can be created.
Groups are created for improving communication performance.
By creating Tags in different groups, some Tags can be read at each cycle, some Tags can be read rarely according to specified group cycle parameter.
In this way some PLC values can be read quick, some values can be read slow.
The Tags that read and write to PLC are created in this list. Additionally Tag values can be monitored and set in this list.
Group must be selected to adding or deleting Tags in this list.
If group not selected, Tag values can be monitored or set but Tags can not be added or deleted.
By selecting the group, only the tags, which belongs to that group, are listed.
Tags that belong to station
Tag Creating and Deleting Operations:
Bottom line of the Tag List will be ready for the creating Tag after selecting the group.
Adress Column: Tag's address inside the PLC should be entered this in column. The Tag which will read and write to register will be created by pressing Enter key after typing register address.
Tag List menu opens when right mouse button clicked on Tag List.
On Tag List menu;
Insert, inserts new Tag above the selected Tag.
Cut, cuts selected row or rows.
Copy, copies selected row or rows.
Paste, pastes copies or cut tags.
Delete, deletes selected row or rows.
Monitoring and Setting Tag Values
Tag values that inside the PLC can be monitored and set in this tab. Network connection must be activated to do this.
Activating Network Connection
Created Network connection can be activated by clicking on Connect button that located in the S7-300/400 MPI toolbar or by clicking Connect button on the WinTr toolbar.
Connect Button that located on WinTr Toolbar activates all Networks.
Connect button on the S7-300/400 MPI tab toolbar activates only selected Network.
Disconnecting Network
If all networks activated by Connect button on the WinTr toolbar, all network connections will be disconnected if pressed again same button.
If Disconnect button which on the S7-300/400 MPI tab's toolbar pressed, network will be disconnected just for a time then it will reactivated immediately.
If Network connection activated by Connect button on the S7-300/400 MPI toolbar, next Disconnect button will deactivate the network.
Status Strip:
StatusStrip that located at the bottom of the S7-300/400 MPI tab, contains information about Network connection.
Gap between the bytes that will read has negative effect on communication performance also.
Following 2 illustarations showing lower performance communication.
Name, determines station's name in the SCADA.
Delete, deletes the station.
Determining station address
S7-300/400 MPI tab Connect button
WinTr can connect multiple PLCs from different serial ports with MPI adapters. Serial port based USB adapter can be used as a S7 adapter.
PLC Vcom Software, that used for that adapters, should be minimum 2.68 version.
Maximum connected PLC count specified by PC's Com port count and it can be extended by USB-Serial converters. This means each MPI Network can contain single PLC. PLC's tag values read and written asynchronously. In this way, increasing PLC count has no effect on communication speed.
PC Baudrate and MPI Baudrate
