Error :st_prep_line() move time is NAN

Hello,

I recently had the error :
st_prep_line() move time is NAN

It was during manual motion (typing command using a custom made software).
Below is the only extract I got from the logs :

{"qr":28,"qi":1,"qo":1}
{"qr":27,"qi":1,"qo":0}
{"sr":{"posx":1.516,"feed":1000.00,"vel":1000.00,"momo":1}}
{"sr":{"posx":3.182}}
{"sr":{"posx":4.115,"vel":8.52}}
{"qr":27,"qi":1,"qo":0}
{"sr":{"posx":3.959,"feed":100.00,"vel":100.00}}
{"sr":{"posx":3.792}}
{"sr":{"posx":3.634}}
{"sr":{"posx":3.467}}
{"sr":{"posx":3.301}}
{"sr":{"posx":3.142}}
{"sr":{"posx":3.012,"vel":9.96}}
{"qr":27,"qi":1,"qo":0}
{"sr":{"posx":1.512,"feed":1000.00,"vel":1000.00}}
{"sr":{"posx":297.000,"vel":0.00}}
{"qr":28,"qi":0,"qo":1}
{"sr":{"posx":0.000,"feed":10000.00,"coor":1,"dist":0,"momo":4,"stat":3}}
{"qr":28,"qi":1,"qo":1}
{"xsv":1500}

{"r":{"xsv":1500},"f":[1,0,13,4562]}
G28.2X0

{"r":{"gc":"G28.2X0"},"f":[1,0,8,299]}
{"sr":{"coor":0,"dist":1,"stat":9}}
{"qr":28,"qi":1,"qo":1}
{"qr":27,"qi":1,"qo":0}
{"sr":{"posx":2.210,"feed":1500.00,"vel":1500.00,"momo":1}}
{"sr":{"posx":4.533,"vel":519.90}}
{"sr":{"posx":4.545,"vel":7.61}}
{"qr":27,"qi":1,"qo":0}
{"sr":{"posx":4.389,"feed":100.00,"vel":100.00}}
{"sr":{"posx":4.231}}
{"sr":{"posx":4.065}}
{"sr":{"posx":3.898}}
{"sr":{"posx":3.740}}
{"sr":{"posx":3.626,"vel":9.96}}
{"qr":27,"qi":1,"qo":0}
{"sr":{"posx":1.329,"feed":1500.00,"vel":1500.00}}
{"sr":{"posx":297.000,"vel":0.00}}
{"qr":28,"qi":0,"qo":1}
{"qr":28,"qi":1,"qo":1}
G28.2X0

{"r":{"gc":"G28.2X0"},"f":[1,0,8,299]}
{"sr":{"posx":0.000,"feed":10000.00,"momo":4}}
{"qr":28,"qi":1,"qo":1}
{"qr":27,"qi":1,"qo":0}
{"sr":{"posx":2.085,"feed":1500.00,"vel":1500.00,"momo":1}}
{"sr":{"posx":4.494,"vel":980.05}}
{"sr":{"posx":4.545,"vel":7.61}}
{"qr":27,"qi":1,"qo":0}
{"sr":{"posx":4.381,"feed":100.00,"vel":100.00}}
{"sr":{"posx":4.215}}
{"sr":{"posx":4.056}}
{"sr":{"posx":3.890}}
{"sr":{"posx":3.723}}
{"sr":{"posx":3.651,"vel":9.96}}
{"qr":27,"qi":1,"qo":0}
{"sr":{"posx":1.599,"feed":1500.00,"vel":1500.00}}
{"sr":{"posx":297.000,"vel":0.00}}
{"qr":28,"qi":0,"qo":1}
{"sr":{"posx":0.000,"feed":10000.00,"coor":1,"dist":0,"momo":4,"stat":3}}
{"qr":28,"qi":1,"qo":1}
{"xjh":100000}

{"r":{"xjh":100000},"f":[1,0,15,4029]}
G28.2X0

{"r":{"gc":"G28.2X0"},"f":[1,0,8,299]}
{"sr":{"coor":0,"dist":1,"stat":9}}
{"qr":28,"qi":1,"qo":1}
{"qr":27,"qi":1,"qo":0}
{"sr":{"posx":2.308,"feed":1500.00,"vel":1500.00,"momo":1}}
{"sr":{"posx":4.366,"vel":52.47}}
{"er":{"fb":435.10,"st":31,"msg":"st_prep_line() move time is NAN"}}
prep_null encountered

And another one while playing with the A Axis:

G0A360F3600

{"r":{"gc":"G0A360F3600"},"f":[1,0,12,1899]}
{"sr":{"posa":0.006,"feed":3600.00,"vel":71.25,"stat":5}}
{"qr":27,"qi":1,"qo":0}
{"sr":{"posa":36.420,"vel":10000.00}}
{"sr":{"posa":77.205}}
{"sr":{"posa":117.990}}
{"sr":{"posa":158.775}}
{"sr":{"posa":199.561}}
{"sr":{"posa":240.346}}
{"sr":{"posa":281.130}}
!

{"sr":{"posa":303.400,"vel":2.91,"stat":6}}
%

{"sr":{"vel":0.00,"stat":3}}
G1A360F30

{"er":{"fb":435.10,"st":31,"msg":"st_prep_line() move time is NAN"}}
prep_null encountered!

Note that I’ve been able to run several long job (couple hours) since this error without reproducing it.
I just wanted to mention this.

My settings (I’m not sure they were exactly the same when running into the prep_null error…)

    [fb]  firmware build            435.10
    [fv]  firmware version            0.97
    [hp]  hardware platform           1.00
    [hv]  hardware version            8.00
    [id]  TinyG ID                    9H3583-PXN
    [ja]  junction acceleration 2000000 mm
    [ct]  chordal tolerance           0.010 mm
    [sl]  soft limit enable           0
    [st]  switch type                 1 [0=NO,1=NC]
    [mt]  motor idle timeout        180.00 Sec
    [ej]  enable json mode            0 [0=text,1=JSON]
    [jv]  json verbosity              5 [0=silent,1=footer,2=messages,3=configs,4=linenum,5=verbose]
    [js]  json serialize style        1 [0=relaxed,1=strict]
    [tv]  text verbosity              1 [0=silent,1=verbose]
    [qv]  queue report verbosity      2 [0=off,1=single,2=triple]
    [sv]  status report verbosity     1 [0=off,1=filtered,2=verbose]
    [si]  status interval           250 ms
    [ec]  expand LF to CRLF on TX     0 [0=off,1=on]
    [ee]  enable echo                 0 [0=off,1=on]
    [ex]  enable flow control         1 [0=off,1=XON/XOFF, 2=RTS/CTS]
    [baud] USB baud rate              5 [1=9600,2=19200,3=38400,4=57600,5=115200,6=230400]
    [net]  network mode               0 [0=master]
    [gpl] default gcode plane         0 [0=G17,1=G18,2=G19]
    [gun] default gcode units mode    1 [0=G20,1=G21]
    [gco] default gcode coord system  1 [1-6 (G54-G59)]
    [gpa] default gcode path control  0 [0=G61,1=G61.1,2=G64]
    [gdi] default gcode distance mode 0 [0=G90,1=G91]
    [1ma] m1 map to axis              0 [0=X,1=Y,2=Z...]
    [1sa] m1 step angle               0.900 deg
    [1tr] m1 travel per revolution   32.0000 mm
    [1mi] m1 microsteps               8 [1,2,4,8]
    [1po] m1 polarity                 1 [0=normal,1=reverse]
    [1pm] m1 power management         1 [0=disabled,1=always on,2=in cycle,3=when moving]
    [2ma] m2 map to axis              1 [0=X,1=Y,2=Z...]
    [2sa] m2 step angle               0.900 deg
    [2tr] m2 travel per revolution   32.0000 mm
    [2mi] m2 microsteps               8 [1,2,4,8]
    [2po] m2 polarity                 1 [0=normal,1=reverse]
    [2pm] m2 power management         1 [0=disabled,1=always on,2=in cycle,3=when moving]
    [3ma] m3 map to axis              2 [0=X,1=Y,2=Z...]
    [3sa] m3 step angle               1.800 deg
    [3tr] m3 travel per revolution    2.1170 mm
    [3mi] m3 microsteps               8 [1,2,4,8]
    [3po] m3 polarity                 0 [0=normal,1=reverse]
    [3pm] m3 power management         1 [0=disabled,1=always on,2=in cycle,3=when moving]
    [4ma] m4 map to axis              3 [0=X,1=Y,2=Z...]
    [4sa] m4 step angle               1.800 deg
    [4tr] m4 travel per revolution   75.0000 mm
    [4mi] m4 microsteps               8 [1,2,4,8]
    [4po] m4 polarity                 1 [0=normal,1=reverse]
    [4pm] m4 power management         1 [0=disabled,1=always on,2=in cycle,3=when moving]
    [xam] x axis mode                 1 [standard]
    [xvm] x velocity maximum       1500 mm/min
    [xfr] x feedrate maximum       1500 mm/min
    [xtn] x travel minimum            0.000 mm
    [xtm] x travel maximum          300.000 mm
    [xjm] x jerk maximum           5000 mm/min^3 * 1 million
    [xjh] x jerk homing           30000 mm/min^3 * 1 million
    [xjd] x junction deviation        0.0100 mm (larger is faster)
    [xsn] x switch min                0 [0=off,1=homing,2=limit,3=limit+homing]
    [xsx] x switch max                1 [0=off,1=homing,2=limit,3=limit+homing]
    [xsv] x search velocity        1000 mm/min
    [xlv] x latch velocity          100 mm/min
    [xlb] x latch backoff            20.000 mm
    [xzb] x zero backoff              3.000 mm
    [yam] y axis mode                 1 [standard]
    [yvm] y velocity maximum       1500 mm/min
    [yfr] y feedrate maximum       1500 mm/min
    [ytn] y travel minimum            0.000 mm
    [ytm] y travel maximum          220.000 mm
    [yjm] y jerk maximum           5000 mm/min^3 * 1 million
    [yjh] y jerk homing           30000 mm/min^3 * 1 million
    [yjd] y junction deviation        0.0100 mm (larger is faster)
    [ysn] y switch min                0 [0=off,1=homing,2=limit,3=limit+homing]
    [ysx] y switch max                1 [0=off,1=homing,2=limit,3=limit+homing]
    [ysv] y search velocity        1000 mm/min
    [ylv] y latch velocity          100 mm/min
    [ylb] y latch backoff            20.000 mm
    [yzb] y zero backoff              3.000 mm
    [zam] z axis mode                 1 [standard]
    [zvm] z velocity maximum       1000 mm/min
    [zfr] z feedrate maximum       1000 mm/min
    [ztn] z travel minimum            0.000 mm
    [ztm] z travel maximum          100.000 mm
    [zjm] z jerk maximum             50 mm/min^3 * 1 million
    [zjh] z jerk homing            1000 mm/min^3 * 1 million
    [zjd] z junction deviation        0.0100 mm (larger is faster)
    [zsn] z switch min                0 [0=off,1=homing,2=limit,3=limit+homing]
    [zsx] z switch max                0 [0=off,1=homing,2=limit,3=limit+homing]
    [zsv] z search velocity         800 mm/min
    [zlv] z latch velocity          100 mm/min
    [zlb] z latch backoff            20.000 mm
    [zzb] z zero backoff             10.000 mm
    [aam] a axis mode                 1 [standard]
    [avm] a velocity maximum      48000 deg/min
    [afr] a feedrate maximum      48000 deg/min
    [atn] a travel minimum           -1.000 deg
    [atm] a travel maximum           -1.000 deg
    [ajm] a jerk maximum          24000 deg/min^3 * 1 million
    [ajh] a jerk homing           24000 deg/min^3 * 1 million
    [ajd] a junction deviation        0.1000 deg (larger is faster)
    [ara] a radius value              0.0000 deg
    [asn] a switch min                0 [0=off,1=homing,2=limit,3=limit+homing]
    [asx] a switch max                0 [0=off,1=homing,2=limit,3=limit+homing]
    [asv] a search velocity        6000 deg/min
    [alv] a latch velocity         1000 deg/min
    [alb] a latch backoff             5.000 deg
    [azb] a zero backoff              2.000 deg
    [bam] b axis mode                 0 [disabled]
    [bvm] b velocity maximum       3600 deg/min
    [bfr] b feedrate maximum       3600 deg/min
    [btn] b travel minimum           -1.000 deg
    [btm] b travel maximum           -1.000 deg
    [bjm] b jerk maximum             20 deg/min^3 * 1 million
    [bjd] b junction deviation        0.0100 deg (larger is faster)
    [bra] b radius value              1.0000 deg
    [cam] c axis mode                 0 [disabled]
    [cvm] c velocity maximum       3600 deg/min
    [cfr] c feedrate maximum       3600 deg/min
    [ctn] c travel minimum           -1.000 deg
    [ctm] c travel maximum           -1.000 deg
    [cjm] c jerk maximum             20 deg/min^3 * 1 million
    [cjd] c junction deviation        0.0100 deg (larger is faster)
    [cra] c radius value              1.0000 deg
    [p1frq] pwm frequency               100 Hz
    [p1csl] pwm cw speed lo            1000 RPM
    [p1csh] pwm cw speed hi            2000 RPM
    [p1cpl] pwm cw phase lo           0.125 [0..1]
    [p1cph] pwm cw phase hi           0.200 [0..1]
    [p1wsl] pwm ccw speed lo           1000 RPM
    [p1wsh] pwm ccw speed hi           2000 RPM
    [p1wpl] pwm ccw phase lo          0.125 [0..1]
    [p1wph] pwm ccw phase hi          0.200 [0..1]
    [p1pof] pwm phase off             0.100 [0..1]
    [g54x] g54 x offset               0.000 mm
    [g54y] g54 y offset               0.000 mm
    [g54z] g54 z offset               0.000 mm
    [g54a] g54 a offset               0.000 deg
    [g54b] g54 b offset               0.000 deg
    [g54c] g54 c offset               0.000 deg
    [g55x] g55 x offset             110.000 mm
    [g55y] g55 y offset             110.000 mm
    [g55z] g55 z offset               0.000 mm
    [g55a] g55 a offset               0.000 deg
    [g55b] g55 b offset               0.000 deg
    [g55c] g55 c offset               0.000 deg
    [g56x] g56 x offset             110.000 mm
    [g56y] g56 y offset              20.000 mm
    [g56z] g56 z offset             -10.000 mm
    [g56a] g56 a offset               0.000 deg
    [g56b] g56 b offset               0.000 deg
    [g56c] g56 c offset               0.000 deg
    [g57x] g57 x offset               0.000 mm
    [g57y] g57 y offset               0.000 mm
    [g57z] g57 z offset               0.000 mm
    [g57a] g57 a offset               0.000 deg
    [g57b] g57 b offset               0.000 deg
    [g57c] g57 c offset               0.000 deg
    [g58x] g58 x offset               0.000 mm
    [g58y] g58 y offset               0.000 mm
    [g58z] g58 z offset               0.000 mm
    [g58a] g58 a offset               0.000 deg
    [g58b] g58 b offset               0.000 deg
    [g58c] g58 c offset               0.000 deg
    [g59x] g59 x offset               0.000 mm
    [g59y] g59 y offset               0.000 mm
    [g59z] g59 z offset               0.000 mm
    [g59a] g59 a offset               0.000 deg
    [g59b] g59 b offset               0.000 deg
    [g59c] g59 c offset               0.000 deg
    [g92x] g92 x offset               0.000 mm
    [g92y] g92 y offset               0.000 mm
    [g92z] g92 z offset               0.000 mm
    [g92a] g92 a offset               0.000 deg
    [g92b] g92 b offset               0.000 deg
    [g92c] g92 c offset               0.000 deg
    [g28x] g28 x position             0.000 mm
    [g28y] g28 y position             0.000 mm
    [g28z] g28 z position             0.000 mm
    [g28a] g28 a position             0.000 deg
    [g28b] g28 b position             0.000 deg
    [g28c] g28 c position             0.000 deg
    [g30x] g30 x position             0.000 mm
    [g30y] g30 y position             0.000 mm
    [g30z] g30 z position             0.000 mm
    [g30a] g30 a position             0.000 deg
    [g30b] g30 b position             0.000 deg
    [g30c] g30 c position             0.000 deg