Re-arm for RAMPS 1.4, BLTouch problem

Hello all,

First time poster with a question.
Currently, I'm running a home-made Prusa i3steel Toolson with a Re-arm for RAMPS connected to a RAMPS 1.4 board. Installed it a good while ago but due to RL intervening, had to put it away.
Having picked up where I left, I want to install a BLTouch to the RAMPS board. Having connected the 5VDC from the Re-arm to the RAMPS servo pins, the BLtouch moves at start-up of the printer and the LED is red.



I've changed the config.txt and added the code below. However, if I give any command regarding the BLTouch, it doesn't respond. Other M commands work fine, it's the M280 / M281 ones that don't.
I haven't updated the firmware yet, perhaps that is an issue? I'm still running a 2017 version
According to the Bill of Material, the IC that provides the 5V rail on the Re-arm should be able to deliver more than 1A of current, plenty to power the BLTouch as far as I know.

Do I have the pin-out wrong or is there something else I'm missing?

Thanks for your advice.

# optional Z probe
## Z-Probe (BL Touch)
# See [forum.smoothieware.org]
# And [smoothieware.org]
zprobe.enable                               true                # set to true to enable a zprobe
zprobe.probe_pin                            1.28                # pin probe is attached to if NC remove the !
zprobe.slow_feedrate                        5                   # mm/sec probe feed rate
zprobe.fast_feedrate                        100                 # move feedrate mm/sec
zprobe.probe_height                         5                   # how much above bed to start probe
##BLTouch Servo Settings
switch.servo.enable                         true
switch.servo.input_on_command               M280 S3.0           # M280 S7.5 Would be midway
switch.servo.input_off_command              M280 S7.0           # Same as M280 S0 0% duty cycle, effectivley off
switch.servo.output_pin                     1.20                # Must be a PWM capable pin
switch.servo.output_type                    hwpwm               # H/W PWM output settable
switch.servo.pwm_period_ms                  20                  # Set Period to 20ms (50Hz) - Default is 50Hz

Edited 2 time(s). Last edit at 04/01/2021 07:11AM by LooneyT.

Upgraded smoothie and the probe works, mods can close or delete.