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6.3 The specifications of the encoder input of the printer
The JET Rapid printer offers 3 different signal inputs:
o
An input for RS422 signals
o
An input for HTL signals
o
An input for TTL signals
Each type of input has its own specifications regarding the voltage levels, the input resistance and the
maximum frequency. For high speed applications, the maximum input frequency is of particular
importance.
Input specifications for interface X1 – Input for encoder signals
Pin Description
Pin Description
A
+5 V (max. 400 mA)
G
encoder channel /B RS422
B
GND
H
encoder channel A TTL (5V)
C
+24 V (1)
J
encoder channel B TTL (5V)
D
encoder channel A RS422
K
encoder channel A HTL (24V)
E
encoder channel /A RS422
L
encoder channel B HTL (24V)
F
encoder channel B RS422
M
PowerOn Option
Signal
Parameter
Value
RS422
Input level
Differential: +/-200mV
Input voltage range: -0,3 to 5,5V
Max. frequency
10 MHz
Terminating resistance
120 Ohm
TTL
Input level high
2,4V to 5,5V
Input level low
-0,5V to 0,7V
Max. frequency
500 kHz
Input resistance
1 MOhm
HTL
Input level high
12 to 28V
Input level low
-0,5 to 3,5V
Max. frequency
500 kHz
Input resistance
3.3 kOhm
As the table shows, the RS422 input with 10 MHz allows the highest maximum input frequency.
The TTL and the HTL inputs are designed for a maximum frequency of 500 kHz.
Even encoders for high speed applications cannot provide output frequencies higher than 350 kHz.
Therefore, the inputs of the printer are not the limiting factor regarding the higher encoder frequencies
during high speed printing.
Make sure that the encoder is able to provide the output frequency that is required for the application!