Table of Contents
Advertisement
9
Technical Principles to Aid Usage of MINISCALE PLUS
9.12 Single-Ended Signaling
9.13 Differential Signaling
9.14 Direction of Travel
Sold & Serviced By:
www.servo2go.com
Toll Free Phone: 877-378-0240
Toll Free Fax: 877-378-0249
sales@servo2go.com
sales@servo2go.com
www.servo2go.com
www.servo2go.com
For single-ended signaling, the voltages change relative to a reference potential
(electrical ground). This is a simple and convenient way of transferring data,
requiring just one wire per signal.
The disadvantage is the relatively high susceptibility to interference. This type of
signaling should therefore only be used for short distances and low speeds.
For differential signaling, the signals are described by a voltage difference without
reference to electrical ground. Instead of a single signal conductor, a pair of wires
is used. One wire carries the signal, and the other carries its inverse. The controller
then composes the difference between the two signals into the so-called
difference signal. (e.g. the A + and A - signals become A).
Differential signaling is the better solution for most applications as it is more
tolerant to interference. Couplings to the signals are almost identical for both wires
such that interference is almost eliminated when generating a difference.
The RS422 standard (differential) was specifically developed for larger distances
and higher transfer rates.
If the carriage moves in the direction of the flexprint, the signal on channel A is 90°
ahead of channel B. From this the controller recognizes a positive direction of
travel, meaning that the counter counts upwards. In the other direction, the signal
on channel A is 90° behind channel B. The counter counts downwards.
The counting direction for the analog interface module is reversed.
31
Advertisement
Table of Contents
