GV21002d_e.doc / Sep-13 Page 7 / 11
A, B and Z may at any time also be independent single signals, e.g. from proximities, photocells
etc. Since the level of every channel is selected individually (see DIL-switch), it is possible to
use different levels on the inputs. Consequently it is e.g. possible to take the position
information from the A, /A, B and /B channels of a RS422 encoder, but to add the
corresponding Z index pulse as a HTL signal from a remote photocell
With HTL signals, the switching threshold lies between 6.5 and 8 volts. The input uses an
internal pull-down resistor of 5kOhms.
Every of the two input terminals provides two auxiliary voltage outputs for easy encoder supply:
+5.2 volts/125 mA and +24 volts*/125 mA
*) Output = power supply voltage – 2 volts
2.4. Asymmetric TTL Inputs
Only when exceptionally asymmetric TTL input signals must be processed (i.e. TTL signals
without inverted signal), a 2-position DIL switch located behind the front plate must be set. This
hidden switch becomes accessible by slightly lifting up the front foil at the lower end
(e.g. by means of a small screw driver)
Switch position 1 is responsible for all channels of Input 1
Switch position 2 is responsible for all channels of Input 2
Ex factory both switches are OFF, i.e. any
single-ended operation requires HTL levels
(this is the normal case)
Asymmetric TTL levels are most sensitive to
noise and interference, therefore not suitable for
cable transmission in an industrial environment!
For all general applications please do not touch the DIL switch hidden behind the front plate !
2.5. Outputs
The outputs provide push-pull characteristics. When set to TTL/RS422 level, the corresponding
output swing is always 5 volts. When set to HTL, the output swing depends on the power
supply input (12 – 30volts).
All outputs are short-circuit-proof.
At any time the signal and the appropriate inverted signal are both available at the output, even
when no inverted signal is applied to the input.
