VEICHI SD700 EtherCAT — Er.960 on startup, clears after few F2 presses — why?
Platform: LinuxCNC 2.9.8, Debian, kernel 6.12.57+deb13-rt-amd64 (PREEMPT_RT)
Drive: VEICHI SD700 EtherCAT servo drive (firmware V1.2)
Interface: linuxcnc-ethercat (lcec) with cia402 component
Mode: CSP (Cyclic Synchronous Position), 1ms servo periodWhat's happeningEvery time I start LinuxCNC, the drive shows
Er.960 (SYNC0 synchronous frame loss) for the first 15-30 seconds. During this time pressing F2 gives:
Code:
joint 0 amplifier fault
emc/task/taskintf.cc 976: Error on joint 0, command number 56
After pressing F2 several times over 15-30 seconds, the drive eventually shows
"88" (operating state), I hear a click from the motor, and everything works fine after that — jogging, position feedback, motion programs all stable.My question is:
why does Er.960 appear at startup and what is actually happening when F2 eventually causes it to go away?System latencyThis is likely relevant. My machine is an AMD Ryzen system on a Shenzhen Meigao generic motherboard. Latency-test shows:
Code:
Servo thread (1ms): Max Jitter = 85,000 ns (85µs)
Base thread (25µs): Max Jitter = 58,000 ns (58µs)
I have tried:
- CPU governor set to performance
- C-states disabled via cpupower
- nomodeset (amdgpu blacklisted)
- isolcpus, nohz_full, rcu_nocbs kernel parameters
- idle=poll
None brought jitter below ~80µs — likely SMM interrupts from locked-down BIOS on this generic hardware.Current workaroundUsing
(500µs) in dcConf which helps the drive lock faster but doesn't eliminate the startup Er.960 completely.Config filessd700.xml
Code:
<?xml version="1.0"?>
<masters>
<master idx="0" appTimePeriod="1000000" refClockSyncCycles="1">
<slave idx="0"
type="generic"
vid="00850104"
pid="01030507"
name="x"
configPdos="true">
<dcConf assignActivate="300" sync0Cycle="*1" sync0Shift="500000"/>
<sdoConfig idx="6060" subIdx="00">
<sdoDataRaw data="08"/>
</sdoConfig>
<syncManager idx="2" dir="out">
<pdo idx="1601">
<pdoEntry idx="6040" subIdx="00" bitLen="16" halPin="control-word" halType="u32"/>
<pdoEntry idx="607A" subIdx="00" bitLen="32" halPin="target-position" halType="s32"/>
<pdoEntry idx="60FF" subIdx="00" bitLen="32" halPin="target-velocity" halType="s32"/>
</pdo>
</syncManager>
<syncManager idx="3" dir="in">
<pdo idx="1A01">
<pdoEntry idx="6041" subIdx="00" bitLen="16" halPin="status-word" halType="u32"/>
<pdoEntry idx="6064" subIdx="00" bitLen="32" halPin="position-actual-value" halType="s32"/>
<pdoEntry idx="606C" subIdx="00" bitLen="32" halPin="velocity-actual-value" halType="s32"/>
</pdo>
</syncManager>
</slave>
</master>
</masters>
sd700.hal
Code:
loadusr -W lcec_conf sd700.xml
loadrt lcec
loadrt [KINS]KINEMATICS
loadrt [EMCMOT]EMCMOT servo_period_nsec=[EMCMOT]SERVO_PERIOD num_joints=[KINS]JOINTS
loadrt cia402 count=1
addf lcec.read-all servo-thread
addf cia402.0.read-all servo-thread
addf motion-command-handler servo-thread
addf motion-controller servo-thread
addf cia402.0.write-all servo-thread
addf lcec.write-all servo-thread
net x-status-word lcec.0.x.status-word => cia402.0.statusword
net x-control-word cia402.0.controlword => lcec.0.x.control-word
net x-pos-raw lcec.0.x.position-actual-value => cia402.0.drv-actual-position
net x-tgt-raw cia402.0.drv-target-position => lcec.0.x.target-position
net x-pos-cmd joint.0.motor-pos-cmd => cia402.0.pos-cmd
net x-pos-fb cia402.0.pos-fb => joint.0.motor-pos-fb
net x-enable joint.0.amp-enable-out => cia402.0.enable
net x-fault cia402.0.drv-fault => joint.0.amp-fault-in
setp cia402.0.pos-scale 10000
setp iocontrol.0.emc-enable-in 1
net tool-prep iocontrol.0.tool-prepare => iocontrol.0.tool-prepared
net tool-chg iocontrol.0.tool-change => iocontrol.0.tool-changed
sd700.ini
Code:
[EMC]
MACHINE = sd700-test
VERSION = 1.1
[DISPLAY]
DISPLAY = axis
CYCLE_TIME = 0.100
[TASK]
TASK = milltask
CYCLE_TIME = 0.010
[RS274NGC]
PARAMETER_FILE = linuxcnc.var
[EMCMOT]
EMCMOT = motmod
COMM_TIMEOUT = 1.0
SERVO_PERIOD = 1000000
[HAL]
HALFILE = sd700.hal
[KINS]
KINEMATICS = trivkins coordinates=X
JOINTS = 1
[TRAJ]
COORDINATES = X
LINEAR_UNITS = mm
ANGULAR_UNITS = degree
MAX_LINEAR_VELOCITY = 5
MAX_LINEAR_ACCELERATION = 20
[EMCIO]
EMCIO = io
CYCLE_TIME = 0.100
TOOL_TABLE = tool.tbl
[AXIS_X]
MAX_VELOCITY = 5
MAX_ACCELERATION = 20
MIN_LIMIT = -9999
MAX_LIMIT = 9999
[JOINT_0]
TYPE = LINEAR
HOME = 0.0
MAX_VELOCITY = 5
MAX_ACCELERATION = 20
MIN_LIMIT = -9999
MAX_LIMIT = 9999
FERROR = 50
MIN_FERROR = 5
SCALE = 10000
HOME_SEARCH_VEL = 0
HOME_LATCH_VEL = 0
HOME_SEQUENCE = 0
Specific questions
- Is Er.960 at startup expected behavior on a high-jitter system while DC sync is being acquired, or does it indicate a configuration problem?
- Why does pressing F2 (which sends CIA402 enable controlword) help the drive clear Er.960 and lock onto DC sync? I would not expect an application-layer command to affect DC sync acquisition.
- Is there a way to make the drive more tolerant of sync frame jitter during the initial lock-in period — either via SDO parameters or lcec config?
- Would increasing
help, and what is the recommended value for a high-jitter system?
- Is there a known-good
formula based on measured max jitter? (e.g. shift = 2x max jitter?)
Any insight appreciated. The system works well once locked — just trying to understand the startup behavior and ideally make it more reliable.
