Siemens FM 450-1 - Page 29

24 VDC encoder power supply
1l+/1M voltage is provided on output "24 VDC" to supply an encoder with short circuit-proof 24-
V voltage. The encoder power supply is short-circuit checked.
5 V encoder signals A and /A, B and /B, N and /N
You can connect incremental encoders with 5 V di󹪜erential signals in compliance with RS422,
i.e. incremental encoders with the di󹪜erential signals A and /A, B and /B, N and /N.
The A and /A, B and /B, N and /N signals are connected via the correspondingly labeled terminals
The signals N and /N are only to be connected if you wish to set the counter to the zero mark of
the encoder.
The inputs are not electrically isolated from the S7-400 bus.
24-V encoder signals A*, B* and N*
24 V signals are identi󹪝ed with the letters A*, B* and N*.
You can connect three di󹪜erent types of encoders to each counter:
• Incremental encoders with 24- V signals:
The signals A*, B* and N* are connected via the correspondingly labeled pins.
• Pulse encoders without directional level:
The signal is connected to terminal A*
• Pulse encoders with directional level:
The count signal is connected to the terminal A*. The directional level is connected to
terminal B*.
The inputs are not electrically isolated toward the S7-400 bus.
Input 󹪝lter for 24 V encoder signals
To suppress faults you can assign parameters to the input 󹪝lters (RC elements) with a uniform
󹪝ltering time for the 24 V inputs A*, B* and N*. The following two input 󹪝lters are available for
each counter:
Table 4-2 Input 󹪝lter for 24 V encoder signals
Features Input 󹪝lter 1
(default setting)
Input 󹪝lter 2
Typical input delay 1 μs 15 μs
Maximum count frequency 200 kHz 20 kHz
Minimum pulse width of the count signals 2.5 μs 25 μs
Wiring
4.2 Terminal assignment of the front connector
Counter module FM 450-1
Equipment Manual, 03/2022, A5E03648739-AC 29