Firmware changes for SafetyBox usage with AASD15A

[aj-whirlybird]

1. Alive signal: Frequency signal that changes its state regularly. The SafetyBox uses this signal to detect if the AMC controller is alive.

• implemented in V2.07 quick fix, see:
  https://github.com/tronicgr/AMC-AASD15A-Firmware/blob/master/Beta_Firmware/enc_6dof_AMC_AASD15A_v2_07_quick_fix.zip
• if possible with a pulse time of about 2ms. This frequency should not vary too much with the number of axes, i.e. the state should change after each axis calculation. Thus there are more pulses the more axes are plugged in. Overall, however, the frequency remains about the same, since each axis calculation requires time.
• output on free S3 port, like quick fix.

2. S1: E-Stop/Park/Standby input: In future this signal will be controlled by the SafetyBox. Since it can trigger three states: E-Stop, Standby and Park it is not easy to control. This signal toggles between Park and Standby each time it is pressed. The first status is random and depends on the previous E-stop cycles.
   It would be simpler for the control if the first press of the button always led to standby, i.e. when it is released, standby is always preceded.

3. 2nd E-stop channel: With this signal the control of the drives is extended by a second E-stop channel, which is directly controlled by the SafetyBox.
   This function uses SigIn2 on AASD15A drive.
   Parameter change: Pn053 = 7 (EMG).

• 2nd E-stop channel: This is the biggest change!
• Signal: on 25p D-Sub pin 7
• Hardware: all pin 7 have to connect together
• Firmware: I hope there's nothing to do.
• Test: when an E-stop occurs, the SafetyBox sets the S1 input on the AMC controller to LOW and also the pin 7 at every D-Sub connector. This should work without firmware changes