SINUMERIK 828D Common Machine Data (MD) Quick Reference — Axis / Spindle / Referencing / Soft Limits

1. First, what 828D MD is and how to read it

A common field question is “where do I change this MD, and to what value”. Three things first:

• MD = Machine Data — parameters that describe what this machine’s axes, spindle, drive train and monitoring look like. They are one of three layers: NC MD (the “definition”), drive parameters (p-prefixed, at drive level, the “execution”), and PLC (the “sequence and enabling”).
• How to read them: go to Diagnostics → Machine data (or the commissioning screen), filter by axis / channel / general; you can also type the MD number directly into the search box. An alarm screen often links the relevant MD as well.
• Version differences: 828D and 840D sl share the vast majority of MD numbers, but default values — and occasionally an individual MD — differ by firmware / PPU version. Every value in this article is a common value; before you touch anything, trust the current value shown on this machine’s diagnostics screen and its parameter sheet.

The MD number band itself hints at the function, which helps you locate quickly:

MD band	Rough function	Typical examples
30xxx	axis / encoder basic config	32100 direction, 31020 encoder resolution, 31040 direct measurement
31xxx	measuring system / drive ratio	31030 lead screw pitch, 31050/31060 drive:axis ratio, 31070/31080 gearbox ratio
32xxx	velocity / position loop / jerk	32000 max axis velocity, 32200 position loop gain, 32300 max acceleration, 32431 jerk
34xxx	referencing / zero point	34010–34210 reference speeds, ref point position, encoder ref state
35xxx	spindle	35000 spindle assignment, 35100 max speed, 35110/35130 per-gear limits
36xxx	monitoring / soft limit / position tol.	36100/36110 soft limit, 36200 velocity monitoring, 36030 rest tolerance

2. Axis basic configuration (drive-train conversion)

These decide “when the motor turns one revolution, how far the table moves and where the system reads”:

MD	Name (common)	Purpose
32100	AX_MOTION_DIR	Axis motion direction (motor direction, NOT feedback polarity) — wrong value reverses the axis
31020	ENC_RESOL	Encoder pulses / resolution per revolution (for linear scales, resolution related to grating pitch)
31030	LEADSCREW_PITCH	Lead screw pitch (linear axis); rotary axis fills 360 or the matching angle
31040	ENC_IS_DIRECT[0]	Direct measuring system? (1 = scale/direct, 0 = semi-closed motor encoder)
31050 / 31060	DRIVE_AX_RATIO_NUMERA / DENOMI	Drive-side : axis-side reduction ratio (numerator / denominator)
31070 / 31080	GEARBOX_RATIO_NUMERA / DENOMI[0]	Gearbox stage reduction ratios (multi-stage gearboxes)

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Semi-closed vs full-closed loop: reading only the motor-end encoder is semi-closed (31040=0); adding a scale that reads the table makes it full-closed (31040=1). Full-closed is more accurate but more sensitive to tuning and vibration — do not flip 31040 to 1 just for “better accuracy”; without the mechanics and scale being right it only gets more unstable.

3. Velocity, acceleration and jerk (the most mis-edited section)

MD	Name (common)	Purpose
32000	MAX_AX_VELO	Maximum axis velocity (geometric hard limit, mm/min)
32010	JOG_VELO_RAPID	Rapid velocity in jog mode
32020	JOG_VELO	Jog axis velocity (handwheel excluded)
32200	POSCTRL_GAIN[0]	Position loop gain Kv (NOT a velocity limit!)
32300	MAX_AX_ACC	Maximum axis acceleration
32431	MAX_AX_JERK[0]	Jerk limit in automatic mode
32430 / 32420	JOG_AND_POS_MAX_JERK / _ENABLE	Jerk value and enable in manual / positioning mode

🚨 The most important correction: MD32200 is the position loop gain (Kv), often mistaken for a “velocity limit” and edited as such. It sets the stiffness of the position loop — too high follows tightly but oscillates easily, too low is stable but “soft” positioning. The axis velocity limit is MD32000, and the monitoring threshold that “watches whether you overspeed” is MD36200 (see section 6). The three roles are completely different — do not mix them:

Jerk (MD32431 etc.) is the rate of change of acceleration; tuned well it removes the shock/vibration at start and direction reversal. Axes that interpolate together must have the same jerk performance, or coupled motion feels awkward.

4. Spindle data

MD	Name (common)	Purpose
35000	SPIND_ASSIGN_TO_MACHAX[0]	Define this axis as spindle (=1 speed-control mode, =0 not spindle)
35010	GEAR_STEP_CHANGE_ENABLE	Gear-step change enable (multi-gear spindles)
35100	SPIND_VELO_LIMIT	Maximum spindle speed (must not exceed MD36200)
35110 / 35130	GEAR_STEP_MAX_VELO / _LIMIT[0]	Per-gear max speed / max speed limit
35120 / 35140	GEAR_STEP_MIN_VELO / _LIMIT[0]	Per-gear min speed / min speed limit
35400	SPIND_POSCTRL_VELO_LIMIT	Speed limit during spindle positioning (C-axis / orientation)
35150	— (speed tolerance)	Allowed deviation of actual vs commanded spindle speed (default 0.1; over it alarms)
35500	— (feed at speed)	=1 allows feed only after spindle reaches set speed

Spindle speed has four limits (loosest to tightest): per-gear max MD35110/35130 → velocity monitoring threshold MD36200 → max spindle speed MD35100 (and not above 36200) → plus channel-level SD43220 etc. When the commanded speed is capped, see which number the actual value is stuck at.

5. Referencing and zero point

MD	Name (common)	Purpose
34010	REFP_CAM_DIR_IS_MINUS	Reference in negative direction?
34020	REFP_VELO_SEARCH_CAM	Speed to search the reference cam/switch
34040	REFP_VELO_SEARCH_MARKER	Speed to search the zero pulse (grid)
34060	REFP_MAX_MARKER_DIST	Max distance to find the reference mark
34070	REFP_VELO_POS	Positioning speed to the reference point
34100	REFP_SET_POS	Reference point position relative to machine coordinate system
34210	ENC_REFP_STATE[0]	Absolute encoder commissioning state (set to “uncalibrated” then reference to write)

On an absolute encoder (scale / motor absolute) the first power-up must set 34210 to uncalibrated then execute referencing, so the system writes the current position into the encoder. Just editing 34100 without referencing makes the position drift after power loss.

6. Soft limits and monitoring (source of crashes and positioning alarms)

MD	Name (common)	Purpose
36100	POS_LIMIT_MINUS	First soft limit (negative)
36110	POS_LIMIT_PLUS	First soft limit (positive)
36120 / 36130	Second soft limit neg / pos	A second, further-out limit
36200	AX_VELO_LIMIT[0]	Velocity monitoring threshold (sustained overspeed → monitoring alarm)
36000 / 36010 / 36030	coarse / fine in-position / rest tol.	Used by spindle orientation (M19) and C-axis indexing; 25040 standstill error alarm is often temporarily eased by raising 36030

🚨 A soft-limit change may not take effect until you reference. The first soft limits 36100/36110 only truly constrain travel after referencing; before referencing the system does not know where it is, and the limit is effectively void. That is exactly where crash risk lives.

7. PLC user data and commissioning cautions

• MD14510 / 14512 / 14514 are PLC user data (manufacturer-defined) — machine builders use them for custom panel buttons, magazine levels, coolant delay, etc. What each bit means is known only to this machine’s PLC ladder. Ask what they mean on this machine before changing; do not copy another machine’s table.
• MD change rules: ① record the original value in a “commissioning .md / backup” before changing; ② many MDs need an NCK reset / power cycle to take effect, and soft-limit / spindle ones often need referencing or a PLC reset; ③ change one item at a time and test it; ④ if it breaks, restore from the saved “commissioning .md” or an ALL backup.
• PLC alarm texts (e.g. the 7000-band) live in the PLC alarm help and correspond to A addresses in the ladder — a different layer from the NC MD discussed here.

FAQ

Are 828D MD numbers the same as 840D sl, can I just copy them?

Most MD numbers are shared (the 30xxx/31xxx/32xxx/34xxx/35xxx/36xxx bands are essentially the same across both), but defaults and occasionally an individual MD differ by firmware / PPU version. Never copy a whole table from another machine — use this machine’s current diagnostics value as the baseline, change only the one item you are sure of, and note the original. Every value here is a common field value, not a fixed value for any specific machine.

I changed MD32200 and now the axis will not move or it vibrates — why?

Because MD32200 is the position loop gain Kv, not a velocity limit. Too high makes the position loop too “stiff” and any slight mechanical backlash / insufficient rigidity triggers vibration or overshoot; too low and the axis “does not follow tightly”, positioning is soft and the surface finish suffers. The axis velocity limit is MD32000, and the overspeed monitoring threshold is MD36200 — three different roles, so do not edit 32200 as a speed cap. To cap speed edit 32000; to deal with overspeed alarms edit 36200.

I changed an MD but it did not take effect — why?

Two classes of cause: ① No reset — many MDs need an NCK reset or power cycle to load; soft-limit and spindle related ones often need referencing or a PLC reset to truly constrain. ② Wrong layer — treating an NC MD as a drive p-parameter, or a PLC user data (14510 etc.) as an NC axis parameter. Before changing, confirm which layer the MD belongs to, and save the original in a “commissioning .md” so you can roll back if it breaks.

Last updated: 2026-10-27

Further reading (EN): SINUMERIK 828D After a Servo-Motor / Encoder Swap — the full referencing and encoder-adjustment MD walkthrough (34000-34210), including the MD34210 state machine and the POWER ON reset requirement.

Further reading (EN): Setting Data (SD) vs Machine Data (MD) on SINUMERIK 828D — beyond the common MD list, split “machine configuration” from “running parameters”: the number range carries the scope, and the activation type decides when a change takes effect.