SIMOREG 6RA70 Siemens DC Master Variable Speed DC Drive
Design & Mode of Operation
– Functions of Inputs and Outputs

Design and Mode of Operation6RA70 DC Master

Functions of inputs and outputs

Analog selectable inputs

After conversion to a digital value, the quantity at the analog inputs can be flexibly adjusted in terms of normalization, filtering, sign selection and offset via parameters. Since these values are available as connectors, the analog inputs can also act as a main setpoint or an additional setpoint or limitation.

Analog outputs

The actual current is output as a real-time quantity at terminal 12. The output can be parameter ized as a bipolar quantity or absolute value, with selectable polarity.

Selectable analog outputs are provided for the output of other analog signals, in the form of a bipolar signal or absolute value. The normalization, offset, polarity and a filtering time can also be parameterized. The required output quantities are selected by means of connector numbers specified at intervention points. Possible outputs are, for example, actual speed, rampfunction generator output, current setpoint, line voltage, etc.

Binary inputs

  • Switch-on/Shutdown (OFF1) via terminal 37
    This terminal function is ANDed with the control bit of the serial interface. With an H signal applied to terminal 37, the main contactor (terminal 109/110) is energized via an internal sequence control. If an H signal is applied to terminal 38 (enable operation), then the controllers are enabled. The drive accelerates at the speed setpoint up to operating speed. With an L signal at terminal 37, the drive is decelerated along the deceleration ramp down to speed n < nmin. When the brake control delay has expired, the controllers are disabled and the main contactor de-energized when I = 0. The field current is then reduced to its standstill value (parameterizable) after a parameterizable delay following main contactor dropout has expired.
  • Enable operation via terminal 38
    This function is ANDed with the control bit of the serial interface. The controllers are enabled with an H signal applied to terminal 38. With an L signal at terminal 38, the controllers are disabled and, at I = 0, the pulses are disabled too. The “Enable operation” signal has high priority, i.e. if it changes to “L” during operation, the effect is always I = 0, causing the drive to coast to a standstill.

Binary selectable inputs: Further binary input terminals are provided for optional function selections. A binector number is assigned to each assignable function terminal for use for control functions.

Examples of binary input functions:

  • Voltage disconnect (OFF2): With an OFF2 (low) signal, the controllers are disabled instantaneously, the armature circuit current reduced and, when I = 0, the main contactor de-energized. The drive coasts down in an uncontrolled manner.
  • Fast stop (OFF3): With a fast stop (low) signal, the speed setpoint at the speed controller input is set to zero and the drive braked along the current limit (separate current limit can be parameterized for fast stop). When n < nmin, I = 0 is input on expiry of the brake control delay time and the main contactor finally de-energized.
  • INCH: The inching function is available with an L signal at terminal 37, an H signal at terminal 38 and activation of inching mode. In active inching mode, the main contactor is energized and the drive accelerated to a parameterized inching setpoint. When the inching signal is cancelled, the drive is braked down to n < nmin: the controllers are then disabled and the main contactor de-energized after a parameterizable delay (0 to 60 s) has elapsed. It is also possible to select whether the ramp-function generator must be active in inching mode or whether a ramp-up time = ramp-down time = 0 should be applied.

Binary outputs

Selectable signalling functions are available at binary output terminals (open emitter output). Any binector quantity – chosen via the appropriate selection parameter – can be output at each terminal. The polarity of the output signal and a settable delay (0 to 15 s) can also be parameterized.

Examples of binary output functions:

  • Fault: An L signal is output when a fault message is active.
  • Alarm: An L signal is output when an alarm is active.
  • n < nmin: An H signal is output at speeds of less than nmin’ This signal is used, for example, to active a zero-speed message.
  • Switch-on command for a mechanical brake: A motor brake can be activated via this signal.

When the drive is switched on with the “Drive ON” function and “Enable operation” signal, an H signal is output to release the brake; output of the internal controller enable signal is delayed for a parameterizable period (corresponding to mechanical brake release time). When the drive is stopped via the “Shutdown” or “Fast stop” function, an L signal to close the brake is output when a speed of n < nmin is reached. At the same time, the internal controller enable signal remains active for a parameterizable time period (corresponding to mechanical brake closing time).l = 0 is then input, the pulses disabled and the main contactor de-energized.

A further operating mode can be selected for the “Close brake” signal (L signal at binary selectable output). With this option, there is no delay until n < nmin is reached when “Internal controller disable” is applied (drive is at zero current), but, instead, the (operating) brake is activated at speeds greater than nmln’

An internal controller disable signal is output in response to fault messages, voltage disconnection or cancellation of the “Enable operation” signal at terminal 38 during operation.


Siemens Energy & Automation
SIMOREG DC Master Base Drive Operating Instructions

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