Setting the Station Type to Master
Now that the slaves are defined it's time to add up to two masters to the PROFIBUS network. There is no need to define I/O modules on the masters, as they make use of those defined on their slaves for data transmission. In a similar manner as for slave devices (Figure 9.31), go to the Hardware interface file, right click on the NIM-7 which is to be master and left click on its Module Properties. Use the PROFIBUS option to bring up the dialog which enables the protocol and configures the module as a master. Set the device as Master and left click OK to complete the task. Now assign the NIM-7 to the physical PROFIBUS network in the workspace by right clicking on the module's name in the hardware tree and left clicking Assign network. Use the drop down to choose the PROFIBUS network as you did with the slave device(s) (Figure 9.32).
Setting the Master's Station ID
Right click on PROFIBUS and left click on Properties in the Network View, initiating the Configure Network dialog in Figure 9.53. Left click on Network Assignment to set the masters' Station ID(s).
Figure 9.53. Set the Master Station ID
Assigning Slaves and Group Membership
Using the same dialog as shown in Figure 9.53, left clicking the NIM-7 selection to assign slaves to the master (Figure 9.54). Double left click a slave to move it from Available slaves to the master's Assigned slaves list. This dialog may also be used to place each slave into one or more groups for network management (Figure 9.55). Note that the PROFIBUS Sync and Freeze messages depend on these group assignments.
Figure 9.54. Assign Slaves to a Master
Figure 9.55. Check the Boxes to Assign Slaves to Groups
Adding Broadcasters and Receivers to the Master's Schema
Once the master has its slaves assigned, broadcasts and receivers may be added to its schema and then linked to I/O modules in those assigned slaves (Figure 9.56). Select the appropriate I/O Module from the list and press OK to create the link. Design Pad G4 automatically filters the list of all I/O modules and only shows the compatible types – recall that master receiver operators link to Output Modules in assigned slaves; master broadcast operators link to Input Modules.
Figure 9.56. Link PROFIBUS Master Receiver to I/O Module
Additional PROFIBUS Operator for the Network Master
The following operators are available on the network master to interface with assigned slaves.
Alarm Receiver: Alarm Broadcasts from the slave are read by the master with this operator. The data received specifies the slave's alarm type.
Sync and Freeze: This pair of operators is used to allow the master to read slaves' outputs and write slaves' inputs consistently. The primary use would be to synchronize multiple slaves, change the data on each one, then issue an 'unsync' so all the outputs on all the slaves change at the same time. Slaves need to be arraigned into sync/freeze groups to accomplish this. Sync locks output data on slaves until the master issues an 'unsync'. Freeze locks input data on all slaves until the master issues an 'unfreeze'.
Device Controller: All assigned devices to a particular master may be brought on or offline with this operator. It can also cause pending acyclic messaging to take place between the master and the slave receiving the device control call.
Master Diagnostics: This operator indicates general communication status between the master and its assigned slave devices on the network.
Slave Diagnostics: The operator issues a diagnostic check from the master to a specified slave.
A detailed overview of Design Pad operator functionality (including PROFIBUS operators) is described in the Design Pad Operator Reference publication PDG-TR-2011/13.
Master's PROFIBUS Network Summary Information
You can access the PROFIBUS Master summary information by right-clicking on a logical network icon in the workspace and selecting the Properties item from the drop-down menu.
Figure 9.57. Populated Slave Address Spaces
The Address Space dialog for particular Master describes its memory utilization. The screen shows where all the defined slave I/O module message transactions will reside in the Master's I/O memory. Each listing shows the following information:
Station ID identifies the slave's station number associated with the message.
Slave Name displays the HWI file name and network device ID for the message.
IO Module lists the symbolic name of the I/O module.
Offset identifies the number of bytes to skip in the slave's buffer before reading or writing the transmitted data.
Size identifies how many bytes of data are used in the Master's memory.
Click on Visual Summary for an alternate view of the Master's memory utilization (Figure 9.58).
Figure 9.58. Address Space Visual Summary
