Using Parallel Event Mode

Note: This mode is available only in firmware version 19980706 and later.

This mode is intended for use with devices that can provide parallel outputs, such as PLCs and thumb-wheel switches. Commands may be given to up to four axes at a time, which is useful for PLCs whose scan times are too long to use Parallel Position mode—which can issue only one command per scan—and Command mode—which can issue a command every two scans.

This mode utilizes the RMC’s Event Control feature; you should be familiar with this feature before using this mode. Each command consists of an 8-bit Event Control step number for the receiving axis to begin executing and a Trigger input.

When used with thumb-wheels, some or all step-number inputs should be tied to the thumb-wheel, and a push-on/push-off button should be tied to the Trigger input.

Refer to Features Shared by All Modes for details on input and output assignments that are common to all modes.

Basic Operation

This mode is unique in that it can utilize both the Communication DI/O and Sensor DI/O. Each of the DI/O modules can command two axes. When a command is given in Parallel Event mode, an event sequence begins on the commanded axis at the Event Step number given on the inputs. The following input/output assignments are used:

CPU DI/O:
Input 0	Run/Stop. Described in Features Shared by All Modes.
Input 1	Unused.
Output 0	Ready. Described in Features Shared by All Modes.
Output 1	Acknowledge. Described in Features Shared by All Modes.
Communication DI/O:
Inputs 0-7	Axis 0 Command Event Step (in binary)
Inputs 8-15	Axis 1 Command Event Step (in binary)
Input 16	Axis 0 Command Trigger
Input 17	Axis 1 Command Trigger
Outputs 0-7	Described in Features Shared by All Modes.
Sensor DI/O:
Inputs 0-7	Axis 2 Command Event Step (in binary)
Inputs 8-15	Axis 3 Command Event Step (in binary)
Input 16	Axis 2 Command Trigger
Input 17	Axis 3 Command Trigger
Outputs 0-7	User-controlled with Set Outputs and Reset Outputs commands.

The CPU inputs, CPU outputs, and DI/O outputs are described in Features Shared by All Modes.

The following three items must be true for a new command to be issued:

The Run/Stop (CPU input 0) line must be high.
The Trigger input for the axis must have changed states (toggled) from the last command issued on the axis.
The eight event step inputs and the trigger input for the axis must all be stable for the number of milliseconds given by the Input Filter value, described below.

Once all of these conditions are satisfied for an axis, a Start Events (E) command is issued to the axis, using the Event Step number representing the axis’s DI/O inputs as the first event in the sequence.

All communications occurring on one axis’s input lines are independent of the communications taking place on other axes’ input lines. Therefore, multiple commands can be issued at once.

Configuring Parallel Event Mode

This is done using the Parallel Event Mode Options dialog box. To use this dialog box:

On the Tools menu, click Module Configuration.
In the Slots list, click the Comm Digital I/O item.
Click Slot options.
In the DI/O mode list, click Parallel Event.
Click Mode options.
Select the desired options.
Click OK.
Click Update RMC.
The Update Module Configuration dialog box will be displayed to indicate the progress. If the module could not be reset automatically, you may be prompted to reset the module manually.

To Set the Input Filter

When a new event number is written to an axis, all eight event-number bits plus the trigger bit for the same axis must be updated simultaneously. This will never happen exactly at the same time, so an input filter must be used. The input filter setting is used to configure the number of milliseconds over which all nine inputs for an axis must hold their values before the new value is considered a command.

User-defined Outputs

As described in Features Shared by All Modes, many of the digital outputs are pre-defined, as described in that topic. However, under Parallel Event mode, it is often useful to reserve one or more of these outputs to be triggered explicitly by the event step table (for example, when a sequence of events finish, an output can be set high). Check the boxes of the output numbers you wish to reserve for this purpose. Depending on the number of axes your RMC model offers, one or more of the outputs may be unavailable but checked. Since these outputs are not predefined the user must define them.