Siemens simovert masterdrives Compendium

Technology Option F01 08.2012
6SE7087-6QX70 (Version AN) Siemens AG
9-32 Compendium Motion Control SIMOVERT MASTERDRIVES
9.4.7 Pulse encoder evaluation [250, 255]
The pulse encoder generates two pulse tracks displaced by 90° and
one zero pulse per revolution. Because of the operating principle of the
pulse encoder, it only reproduces changes in position. In order to
determine the absolute position from 0° to 360°, it is necessary to
reference the system (e.g. by crossing the zero pulse). These
characteristics mean that the pulse encoder can only be configured for
asynchronous machines.
Evaluation of the pulse encoder is handled by a sensor board (SBP)
[250, 255].
The permissible cable length depends on the encoder selected. Various
charts are produced according to the interface. Bipolar encoders allow
the longest cables to be used. Unipolar encoders restrict the length of
cable which may be used. In the case of HTL encoders, the maximum
output current of the encoder has a major impact on the transmission
distance that can be achieved. The higher the maximum output current,
the greater the distance possible (the encoder must reverse the cable
capacitance charge on every pulse).
With the SBP sensor board, the terminating resistors can also be used
for HTL signals (this is a "dynamic cable terminator" which keeps power
loss to a minimum).
In the chart below, the maximum permissible cable lengths for
TTL/RS422 encoders are plotted against the pulse frequency:
Pulse frequency [kHz]
150m
100
150
200 250 300 400
300m
100m
150m
Cable length
Cable length for pulse encoders
with TTL/RS422 signals
Fig. 9-13 Maximum cable lengths for pulse encoders with TTL/RS422 signals
Principle
Cable length

Siemens simovert masterdrives Specifications

General

Brand	Siemens
Model	simovert masterdrives
Category	DC Drives
Language	English