Features Shared by All Modes

There are several details that are common between the Digital I/O modes (Parallel Position, Input to Event, Command, and Parallel Event). These are described here.

Inverting Inputs and Outputs

It is possible to invert any Communication Digital I/O input or output. Refer to Communication Digital I/O for instructions on inverting the bits.

CPU Input 0 - Run/Stop

Note: This special functionality is valid only if there is a DI/O module in the comm (leftmost) slot.

This input is edge-sensitive. On the rising edge (0 to 1 transition), a Set Parameters command is sent to each axis. On the falling edge (1 to 0 transition), a Disable Drive Output command is sent to each axis. This input should be set low when drive or hydraulic power is turned off.

CPU Output 0 - Ready

Note: This special functionality is valid only if there is a DI/O module in the comm (leftmost) slot.

With RMC CPU firmware dating prior to 20011112, this input echoes the Run/Stop input described above. That is, when the axes are initialized because of a rising edge of the Run/Stop input, this output will turn on, and it will go off when the Run/Stop input goes off.

With RMC CPU firmware dating 20011112 or later, the user can also use this output to indicate that an error occurred on a group of axes. If an error bit turns on in the Status Word for any of the selected axes, and that error bit has been set up to trigger a Soft or Hard Stop by the Auto Stop word, then the Ready output will be off even if the Run/Stop output is on. Therefore, the Ready output will be on if the Run/Stop output is on and there are no Auto Stop errors on any of the selected axes.

To select the axes that use this error indication, use the Communication DI/O Options dialog box, as described in Using the Communication Digital I/O. By default no axes are selected, so the behavior matches that of pre-20011112 firmware.

CPU Output 1 - Command Acknowledge

Note: This special functionality is valid only if there is a DI/O module in the comm (leftmost) slot.

This bit toggles each time a new command is received. The criteria for a new command varies on the mode used; refer to the appropriate mode description for details. This output deglitches inputs and simplifies programming.

Digital Inputs

The digital inputs are reserved by the current mode you are using. Refer to Input to Event Mode, Parallel Position Mode, Command Mode, or Parallel Event Mode for details.

Digital Outputs

The Communication Digital I/O has eight digital outputs. When using Input to Event Mode, Parallel Position Mode, or Parallel Event Mode, these inputs can be used in the following three ways. Refer to Command Mode for details on their use in that mode.

• In Position: As many outputs as installed axes are used to indicate when the In Position bit of the Status word is set. These bits start at bit 0. Therefore, output 0 represents the In Position bit of axis 0, output 1 represents the In Position bit of axis 1, etc.

• Auto Stop Error: If there are four or fewer axes in the motion controller, then one additional bit per axis is reserved to indicate when an axis has stopped due to an error. This bit is set when an error occurs—as marked in the Status word—which is also set in the Auto Stop word. These bits start at bit 4. Therefore, output 4 represents the Auto Stop Error bit for axis 0, output 5 represents the Auto Stop Error bit for axis 1, etc.

• User Controlled: Any bits still unused can be set and reset using the Set Outputs and Reset Outputs commands. Attempts to use these commands on bits reserved for In Position or Auto Stop will be ignored. In Input to Event and Parallel Event modes, bits that default to being used for In Position and Auto Stop Errors may be overridden to become user controlled. To do this, click Mode options from the Communication DI/O Options dialog box.

The following charts show the bit-use defaults for some RMC configurations:

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