Siemens Reference of Data: Essential 7 Data Tools

• 1
  What the Siemens reference of data actually covers
• 2
  Machine data: the limits everything else is checked against
• 3
  Setting data: how the workpiece is tied to the machine
• 4
  Tool data: geometry, wear and the difference between them
• 5
  User data: cycles, macros and the shop's own layer
• 6
  Backing up the Siemens reference of data in order
• 7
  Comparing the four data areas

On a Siemens 840D sl control, the Siemens reference of data is not one file. It is four data areas the NC kernel reads in a fixed order at power-up. Machine data sets the physical limits of the machine. Setting data holds the offsets that tie the workpiece to the machine. Tool data describes each cutter and its wear. User data is whatever the programmer adds: cycles, macros, R-parameters, work offsets beyond the standard set.

The order matters. Machine data is loaded first because setting data and tool data are validated against the axis limits it defines. If an axis limit is wrong, a perfectly valid tool offset can still trigger a soft-limit alarm, and the operator wastes an hour checking the tool instead of the parameter. That is the single most common misdiagnosis on a new machine install.

Each area has its own edit protection level. Machine data normally sits behind a manufacturer or service password. Setting data and tool data are open to the setup operator. User data sits in between, depending on how the shop assigns access rights. Knowing which level you are in tells you immediately whether the fix is yours to make or a call to the machine builder.

One practical consequence: the reference of data is a read order, not a storage location. The same logical value may live in the NC memory, on the compact flash card, or on an external PC, and the control copies it in at boot. When two copies disagree, the boot sequence decides which one wins.

• 1
  Read orderMachine data, then setting data, then tool data, then user data.
• 2
  ProtectionHigher-level data usually needs a service password to edit.
• 3
  StorageLogical value and physical location are separate concerns.

Machine data describes the hardware. Axis travel limits, maximum axis velocity, spindle minimum and maximum speed, gear step ratios, feed gear stages, and the presence or absence of a measuring system all sit here. On a typical 3-axis vertical mill with 750 × 1,150 × 550 mm travel, the machine data block is what tells the control that Z cannot go past 550 mm.

Two sub-groups are worth separating in your head. General machine data applies across the whole control: language, unit system, memory configuration, and the number of active channels. Channel-specific machine data applies per channel, which is why a dual-channel mill-turn center can run two different spindles with different speed limits at the same time.

Axis-specific machine data is the third and most delicate group. Here you find reference point approach velocity, reference cam position, jerk limits, and the position control loop gain. Changing loop gain on a machine with a worn ball screw can reduce following error on paper while making the axis audibly rough in the cut.

The rule we follow: machine data changes belong to the machine builder or to a trained service engineer with a backup of the original values in hand. If a limit is wrong, you are not tuning a machine, you are correcting an install error, and it should be documented.

Setting data is where the operator lives. It holds work offsets, active tool number and tool edge, feedrate override limits, and the programmable zero offsets. On a Siemens control you will see this as the G54 to G57 family plus the extended frames. These are the numbers you touch every time you load a new fixture.

The key distinction is between a frame and a machine data limit. A frame shifts the coordinate system; it cannot move an axis past a limit stored in machine data. If you enter a Z offset that puts the tool below the machine reference, the control alarms before the motion starts, not after. That is a safety feature, not a fault.

Setting data also carries the active plane, the active feed type (G94 feed per minute versus G95 feed per revolution), and the dry-run feed. Operators sometimes blame the program for a wrong feed when the real cause is a G94/G95 mismatch left over from the previous job. Check the active G-code group before editing the program.

Because setting data changes with every job, it is the area most likely to be wrong at first part. We treat it as disposable: verify against the setup sheet, not against what the last operator left in memory.

• 1
  FramesG54–G57 plus extended offsets shift the zero point.
• 2
  Cannot exceedFrames are still bounded by machine data travel limits.
• 3
  Check firstActive G94/G95 group before blaming the program.

Each tool in the magazine has a data record. It contains the tool type, the number of cutting edges, the geometry length offsets in X and Z (or the full XYZ set on a milling center), the radius or diameter, and a separate wear column. Geometry is what the tool is supposed to be. Wear is what it has become after cutting.

Keeping geometry and wear separate is the whole point. When a tool is replaced, you change geometry and reset wear to zero. When a tool dulls, you adjust wear only. If you edit geometry to compensate for wear, the next tool change deletes your correction and the dimension drifts back. This single habit causes more scrap than any other tool-setting mistake.

Tool data also carries the tool monitoring values: maximum life in minutes or in number of cuts, and the load limit on the spindle or axis. On a 16-station mill-turn center running unattended, a life limit that is set too high will let a drill run until it snaps. Set life from the tool supplier data and shorten it by 20 percent for the first run.

Radius compensation is the other trap. The control needs to know whether the programmed path follows the part edge or the tool center. Get that wrong and every contour is off by one tool radius, which on a Ø10 mm cutter is 5 mm. The machine will cut a clean, accurate, completely wrong part.

User data is everything the shop adds on top of the standard control. That includes custom cycles, macro programs, R-parameter assignments, shop-standard work offset ranges, and any OEM screen forms. It is the layer that makes one shop's 840D sl behave differently from another's, even on identical hardware.

This is also the layer that breaks during a software upgrade. A cycle written for an older control generation may call a data area that has been renamed. The control boots fine, the standard functions work, and one custom cycle throws an error three hours into a run. Before any upgrade, export the user data area and note every custom cycle number.

We keep user data under version control, the same as programs. A cycle that is not in the backup does not exist. On a machine that runs 24 hours, an operator should be able to restore user data from a compact flash card without calling anyone.

For shops running mixed Siemens and Fanuc cells, the user data layer is where the two controls diverge most. The standard ISO code travels; the custom cycles do not. Plan the post-processor around that fact rather than discovering it on the first transfer.