I/O, delays and checkpoints

Digital I/O

The control board's two inputs, two outputs and the E-stop, as the firmware reports them:

state = rbt.io()                 # [in1, in2, out1, out2, estop], or None on a timeout
rbt.write_io(0, 1)               # output 1 high; logical index 0 = the first output
rbt.write_io(1, 0, timeout=1.0)  # raises TimeoutError if not confirmed in time

The firmware's I/O byte is [in1, in2, out1, out2, estop, ...], so logical output 0 is bit 2 of the byte; write_io does the mapping. is_estop_pressed() reads the E-stop alone. A per-call timeout bounds the setup, the retries and the reply; without one the client's defaults apply.

A write is queued with the motion: it takes effect when its turn in the queue comes, and it returns a command index that wait_command() waits on. The pneumatic gripper's open() and close() are output writes of the same kind. While the controller is disabled, after estop() or the E-stop until reset(), a write is refused with SYS_CONTROLLER_DISABLED, like a move.

Switching an output at a point of a program

Queue the write between the two moves it belongs between. The output changes when the first move has finished, and the second move starts after it:

rbt.move_l([0, 263, 200, 90, 0, 90], speed=0.5, wait=False)   # to the part
rbt.write_io(0, 1)                                              # output 1 high, once the arm is there
rbt.delay(0.5)                                                  # let the valve act
rbt.move_l([0, 263, 242, 90, 0, 90], speed=0.5, wait=False)   # away again
rbt.write_io(0, 0)                                              # output 1 low at the end
rbt.wait_motion()

A checkpoint() is for something outside the robot that must know when the queue reaches a point; the outputs do not need one.

Delays

rbt.delay(1.0)                   # a second of nothing, in the queue

A queued delay holds the arm for its duration at its place in the queue; it is not time.sleep(), which would hold your script and not the robot. A paused queue keeps the delay's remaining time.

Checkpoints

index = rbt.checkpoint("pick_done")
...
rbt.wait_checkpoint("pick_done", timeout=30)

A checkpoint is a labelled marker in the queue; wait_checkpoint() blocks until the queue reaches it, and the status stream reports last_checkpoint. It is how a program synchronises something outside the robot, a conveyor or a camera, with a point in the motion.

Comments

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