1. Description

I/O control handles I/O tasks like coolant, toolchange and E-stop. The signals are turned on and off with G-code or in the case of E-stop in HAL.

I/O Control V2 adds more toolchanger support for communication with the toolchanger.

  • LinuxCNC originated abort and toolchanger fault: iocontrol reliably abort a change operation in progress (tool-change asserted). A toolchanger may at any time signal a fault which will abort the next M6. For instance, a toolchanger finding an empty pocket during a prepare operation should be able to signal a fault to iocontrol, and iocontrol act appropriately when the M6 change operation is executed.

  • Communicate abort/fault cause : let iocontrol know why toolchanger caused an fault, and why iocontrol aborted. This is for UI purposes. It would be a candidate for a #5xxx parameter, and selective display in the UI.

  • No race conditions between iocontrol and toolchanger: the protocol between iocontrol and toolchanger must be unambiguous with respect to which operation is signalled, and if a change operation is aborted or complete.

  • Consistent view of state: Both parties must have a consistent view of the state at any point in time with respect to aborted versus completed, and tool number and pocket.

  • Handshaked signaling an abort/fault: an abort signaled by LinuxCNC to the toolchanger, and a fault indicated from the toolchanger is handshaked to assure reliable signaling, and optionally force lock-step behaviour. Handshaking is optional and can be jumpered in HAL if not needed.

  • Backwards compatibility: A toolchanger ignoring the iocontrol emc-abort line and sticking to old handling will "continue to work" (subject to race condition)

If you have strict timing requirements or simply need more I/O, consider using the realtime I/O provided by motion instead.

2. Usage

INI file options:

[EMCIO] section

Defaults to 2. Setting to 1 will emulate old iocontrol behaviour.

EMCIO = iov2 -support-start-change

You need to explicitly enable the start-change protocol by adding the -support-start-change option; otherwise the start-change pin remains low and start-change-ack is ignored. The reason for this is better backwards compatibility.

[TASK] section

Printf-style template for operator error display (negative toolchanger fault codes). No quoting needed. Example: IO_ERROR = Toolchanger fault %d. Default: toolchanger error %d.

[EMC] section

To get a (quite detailed) trace, set either the RCS debugging flag (0x00000200) to turn on RCS debugging messages all over LinuxCNC or use the new iocontrol debugging bit (0x00001000) only for iov2 messages.

3. Pins

  • iocontrol.0.coolant-flood (bit, out) TRUE when flood coolant is requested.

  • iocontrol.0.coolant-mist (bit, out) TRUE when mist coolant is requested.

  • iocontrol.0.emc-enable-in (bit, in) Should be driven FALSE when an external E-stop condition exists.

  • iocontrol.0.tool-change (bit, out) TRUE when a tool change is requested

  • iocontrol.0.tool-changed (bit, in) Should be driven TRUE when a tool change is completed.

  • iocontrol.0.tool-number (s32, out) Current tool number

  • iocontrol.0.tool-prep-number (s32, out) The number of the next tool, from the RS274NGC T-word

  • iocontrol.0.tool-prep-pocket (s32, out) This is the pocket number (location in the tool storage mechanism) of the tool requested by the most recent T-word.

  • iocontrol.0.tool-prepare (bit, out) TRUE when a Tn tool prepare is requested.

  • iocontrol.0.tool-prepared (bit, in) Should be driven TRUE when a tool prepare is completed.

  • iocontrol.0.user-enable-out (bit, out) FALSE when an internal E-stop condition exists

  • iocontrol.0.user-request-enable (bit, out) TRUE when the user has requested that E-stop be cleared

Additional pins added by I/O Control V2

  • emc-abort: (bit, out) signals emc-originated abort to toolchanger.

  • emc-abort-ack: (bit, in) Acknowledge line from toolchanger for previous signal, or jumpered to abort-tool-change if not used in toolchanger. NB: after signaling an emc-abort, iov2 will block until emc-abort-ack is raised.

  • emc-reason: (S32, out) convey cause for EMC-originated abort to toolchanger. Usage: UI informational. Valid during emc-abort TRUE.

  • start-change: (bit, out) asserted at the very beginning of an M6 operation, before any spindle-off, quill-up, or move-to-toolchange-position operations are executed.

  • start-change-ack: (bit, in) acknowledgment line for start-change.

  • toolchanger-fault: (bit, in) toolchanger signals fault. This line is contionuously monitored. A fault toggles a flag in iocontrol which is reflected in the toolchanger-faulted pin.

  • toolchanger-fault-ack: (bit, out) handshake line for above signal. will be set by iov2 after above fault line TRUE is recognized and deasserted when toolchanger-fault drops. Toolchanger is free to interpret the ack; reading the -ack lines assures fault has been received and acted upon.

  • toolchanger-reason: (S32, in) convey reason code for toolchanger-originated fault to iov2. Usage: signal whether to continue or abort the program, plus UI informational if negative. Read during toolchanger-fault TRUE. Non-zero values will cause an Axis operator operator message or error message, see below.

  • toolchanger-faulted: (bit, out) signals toolchanger-notify line has toggled and toolchanger-reason-code was in the fault range. Next M6 will abort.

  • toolchanger-clear-fault: (bit, in) resets TC fault condition. Deasserts toolchanger-faulted if toolchanger-notify is line FALSE. Usage: UI - e.g., clear fault condition button.

4. Parameters

  • iocontrol.0.tool-prep-index (s32, RO) IO’s internal array index of the prepped tool requested by the most recent T-word. 0 if no tool is prepped. On random toolchanger machines this is tool’s pocket number (i.e., the same as the tool-prep-pocket pin), on non-random toolchanger machines this is a small integer corresponding to the tool’s location in the internal representation of the tool table. This parameter returns to 0 after a successful tool change M6.

5. Communications

If LinuxCNC signals an abort for whatever reason, this is reflected in the emc-abort and emc-reason pins. The toolchanger is expected to acknowledge the emc-abort pin by raising the emc-abort-ack pin - iov2 will block until this is done. If you do not need the abort handshake feature, jumper them as follows:

net emc-abort-ack iocontrol.0.emc-abort iocontrol.0.emc-abort-ack

The emc-reason pin is considered valid during emc-abort being TRUE.

The reason codes are as follows for LinuxCNC internally generated aborts (see emc.hh ca line 321):









  • EMC_ABORT_USER = 100

iov2 adds one more code, namely EMC_ABORT_BY_TOOLCHANGER_FAULT = 101 which is signaled when an M6 aborts due to the toolchanger-faulted pin being TRUE.

To signal toolchanger faults to LinuxCNC, wire the toolchanger-fault pin, and optionally the toolchanger-reason and toolchanger-ack pins.

The toolchanger-fault triggers the fault condition, which is reflected in the toolchanger-faulted pin. This condition can be cleared by asserting the toolchanger-clear-fault pin, provided the toolchanger-fault pin is FALSE.

The value of the toolchanger-reason pin is used as follows:

  • toolchanger-reason > 0 : The toolchange process is not completed and the program continues, however parameter #5060 is set to 1.0 to indicate the fault. Parameter #5601 contains the value of the toolchanger-reason pin.

    • toolchanger-reason = 0 : the program is aborted

    • toolchanger-reason < 0 : the program is aborted and an operator error message is displayed by using the IO_ERROR template.

The usage of the toolchanger-fault-ack pin is optional. It will become TRUE when toolchanger-fault is raised and the toolchanger-reason pin has been read by iov2.