Acceleration with jerk limitation

To couple optimum acceleration performance of the machine with reduced wear on the mechanical parts, you can choose between sudden acceleration and continuous (jerk-free) acceleration. With "jerk-free" acceleration, the velocity characteristic is described by a sinusoidal curve.

Backlash compensation

"Backlash compensation" compensates for mechanical backlash, for example ball screw backlash. Backlash compensation can be entered separately for each axis.

Block search

For testing part programs or after machining has been interrupted, it is possible to select any point in the part program using the block search function in order to start or resume machining at this point. The block search can be executed forward or backward in the part program. The following can be selected as a search destination:

• Block number in the main program
• Number of passes and block number in a subroutine.

CNC programming language

The basis for the CNC programming language is DIN 66025.

Dimensions in metric and inches

Position and gradient values can be entered in the part program in inches. The control can be set to a basic system regardless of the programmed measuring system.

Example: The basic system is metric

An inch system thread is to be machined within a metric program. All data such as tool offsets, zero offsets and feedrates remain metric.

Drift compensation

FM 354

During the constant velocity phase of the axis, the analog speed control's drift is automatically compensated. The function can be selected via system parameters.

Drives for servomotors

FM 354/FM 357-2

The FM 354 and FM 357-2 provide one analog ±10 V interface per axis.

Both the PROFIBUS drives SIMODRIVE 611 universal HR and the POSMO CD/CA/SI and MASTERDRIVES MC can additionally be operated on an FM 357-2 (not with FM 357-2H firmware and HT 6).

Drives for stepper motors

FM 353/FM 357-2

One interface for clock and directional signals is available for each axis on the FM 353 and FM 357-2 for the control of power sections for stepper motors. The stepper motor can be driven via a stepper motor power section. On the FM 357-2, position-controlled operation with incremental and absolute value encoders as well as hybrid operation with analog servo-axes is possible (e.g. 2 axes stepper/2 axes servo).

Follow-up mode

The setpoints are not output by the control, but the control remains synchronized with the machine (follow-up mode). Traverse paths can be checked on the display.

High-speed inputs/output

FM 353/FM 354

Four digital inputs and outputs each are available for high-speed process signals. The following functions can be assigned via machine data:

• High-speed inputs:
  External start, enable, measurement, reference point switch or reversing cams for reference point approach.
• High-speed outputs:
  Position reached (stop), axis movement forward/backward, modification M97/M98, or start enable.

FM 357-2

The FM 357-2 is equipped with 18 high-speed inputs, four of which are used for reference point approach and 2 of which can also be evaluated without a delay for "high-speed measurement". Furthermore, the FM 357-2 has 8 freely-usable high-speed outputs. If required, 2 standard S7-300 I/O modules can be inserted at the right of the FM 357-2 and be operated as high-speed I/O module by defining a "local segment". Authorized modules are 16-bit input/output modules and analog output modules (on request).

Installation and start-up support

A tool is available for each of the FM modules which will be integrated as auxiliary software in STEP 7. This tool is a component of the relevant configuring package, and must be obtained separately.

All FM start-up tools contain screen form-driven start-up assistants, program editors, and diagnostic functions.

In addition, every configuring package is accompanied by a "Getting Started" leaflet intended primarily for newcomers to help them to a successful start.

Languages

The display texts for operator prompting and the system messages and alarms are available in the four languages German, English, French and Italian.

Main programs/subroutines

If machining operations recur frequently, it is advisable to store them in a subroutine. The subroutine is called from a main program (250 passes, for FM 357-2: max. 9999). One subroutine level (for FM 357-2: 11) is possible in a main program.

Measurement on-the-fly

The "Measurement on-the-fly" function enables delay-free storage of the current actual position value by an external switching event - acquisition is performed independently of the internal computer clock. This value can then be post-processed in the CNC program for high-precision length acquisition or print-mark detection.

Monitoring functions

The position controllers contain permanently active monitoring functions which recognize faults in the control, the PLC and the machine at an early stage, so that damage to the workpiece, tool or machine can be avoided. In the event of a fault, the machining sequence is interrupted, and the drive stopped. The cause of the fault is saved, and displayed as an alarm. The PLC is informed at the same time that an alarm is present. Monitoring functions exist for the following areas:

• Read in
• Format
• Measuring circuit
• Encoder and drive
• Enabling signals
• Voltage
• Microprocessors
• Serial interfaces
• Transmission between control and PLC
• System memory and user memory

Multi-point interface MPI

When FM 353, FM 354 and FM 357-2 are used, the SIMATIC S7-300 CPU provides the multi-point interface (MPI).

Operating modes

• AUTOMATIC
  In AUTOMATIC mode, the part programs to be executed are selected and started. Control of AUTOMATIC mode by:
  • Block skip
  • Programmed stop
  • Rapid traverse override
  • AUTOMATIC single block
• MDI (manual data input)
  In MDI mode, it is possible to enter program blocks or sequences of blocks without reference to a main program or subroutine and then to execute them immediately via start.
• JOG
  In JOG mode, it is possible to set up the machine. The axis can be moved in this mode using the direction keys.
• Reference point approach

The modes are supplemented by the functions Preset (set actual value) and Teach-in.

Operator interface, OP7/OP17/OP27

FM 353/FM 354

Standard operating screens are displayed on the OP7 and OP17 for FM 353/FM 354.

FM 357-2

Example operating screen forms for OP17 and MP 270B are delivered with the FM 357-2. These operating screen forms can be loaded and modified using ProTool.

Override/time override

The override acts as a pure velocity override, i.e. it modifies the velocity of the traversing movement by a percentage value. The time override also acts on the set acceleration and brake ramps.

PLC program memory

In the PLC user memory of the PLC CPU, the PLC user program and the user data are stored together with the standard software technology functions.

The memory of the PLC CPU is divided into load memory, working memory, and system memory. The load memory is a permanent memory, and in addition to the data required for execution it also contains data, program and decompilation info. The load memory can be integrated as RAM or read-only memory (flash) or is available in the form of a memory card. When the PLC CPU powers up, the code required for execution and the data from the load memory are loaded into working memory.

All standard S7-300 CPUs can be used in conjunction with FM modules. Depending on the respective FM modules, the minimum recommendations must be observed.

Positioning axes

Positioning axes can execute movements simultaneously with machining, thus reducing non-productive times considerably. They can be used to advantage for controlling workpiece and tool loaders or tool magazines. They can be programmed with an axis-specific feedrate in the part program. Axis movement beyond block boundaries is also possible.

Preset

With the machine function "Preset" (set actual value), the control zero can be redefined within the machine coordinate system. Preset does not move the axes, but a new position value is entered for the current axis positions.

Programmable acceleration

With the "Programmable acceleration" function, it is possible, for example, to modify the axis acceleration in the program to limit mechanical vibration in critical program sections. The path or positioning axis is then accelerated at the programmed value. The maximum acceleration value stored in the control is not exceeded. As part of intelligent motion control, this function provides a more precise workpiece surface.

Reference point approach

When using a machine axis in program-controlled mode, it is important to ensure that the actual values supplied by the measuring system agree with the machine coordinate vales. The reference points (limit switches) are approached at a defined speed. If linear measuring systems with distance-coded reference marks are used, reference point approach is shortened.

Rotary axis

Depending on the application, the traversing range of a rotary axis can be selected to be limited to less than 360 degrees or to be endlessly turning in both directions. Endlessly-turning rotary axes are used for non-circular turning, grinding, and winding.

Software limit switch

Software limit switches limit the traversing range of an axis. The axis stops at the software limit switch.

User memory

All programs and data such as part programs, subroutines, comments, tool offsets and zero offsets can be stored in a common user memory. The user memory is located on the module.