Wishful Coding

Didn't you ever wish your
computer understood you?

Sciento CS-113

After my success with the Cyber arm, I had to try my luck at the Sciento one.

This time I was out of luck with Dutch or English documentation, but my brother found a Spanish PDF, from which I was able to get the needed information using Google Translate.

Unlike the Cyber, the Sciento is controlled by sending actual ASCII commands, rather than stepping the motors directly.

It is a lot smarter than the other arm, as it can remember its position. A list of commands:

  • “Z” Sets the reference point
  • “N” Go to the reference position
  • “C”/”O” Close/open the claw
  • “M100,0,-250,0,0,0” Move the motors for the specified steps.
  • “H7” Save the current position in the specified register(1-100)
  • “P5,500,200,-5,0,0,0” Save the specified position in the specified register(first number, 1-100)
  • “G1” Move to the location in the specified register
  • “S5” Set the motor speed(1-5)
  • “D1” Wait for x seconds. Useless?
  • “L1” Check the limits of the motors. Recommended for testing, off by default.

Note that numbers are represented as ASCII text and that commands are upper-case. All commands are terminated by a carriage return.

A downside to this arm is that in comparison to the one-byte commands for the Cyber, it takes ages to send an ASCII command across, making this arm unsuitable for smooth control with a gamepad.

I programmed a coarse and ugly controller, with buttons for storing positions and moving to them. In the video I’m just stepping through the motions I stored earlier.

The controller is a real mess, based on the Cyber code, and not very interesting.

The code for the arm itself is nice though. Note the use of the actual strobe line, as opposed to the strobe bit in the Cyber code.

import parallel
from time import sleep

p = parallel.Parallel()

def write(s):
    bs = map(ord, s)
    bs.append(13)
    for b in bs:
        p.setData(b)
        p.setDataStrobe(1)
        p.setDataStrobe(0)
        sleep(0.001)

def command(cmd, *params):
    write(cmd+",".join(map(str, params)))

def move(m1=0, m2=0, m3=0, m4=0, m5=0, m6=0):
    "Move a number of steps"
    command("M", m1, m2, m3, m4, m5, m6)

def here(n):
    "Save current position in slot n 1-100"
    command("H", n)

def position(n, m1, m2, m3, m4, m5, m6):
    "Save the specified position in slot n 1-100"
    command("P", n, m1, m2, m3, m4, m5, m6)

def zero():
    "Set the reference point"
    command("Z")

def goto(n):
    "Go to position in slot n 1-100"
    command("G", n)

def home():
    "Return to the reference"
    command("N")

def open():
    "open the claw"
    command("O")

def close():
    "Close the claw"
    command("C")

def speed(n):
    "Set the speed 1-5"
    command("S", n)

def delay(n):
    "Wait for n seconds"
    command("D", n)

def limit(b):
    "enable/disable limits"
    commands("L", b)
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