Siemens S5-135U/155U System Manual page 256

CPUs, Memory Cards, Memory Submodules, Interface Submodules
With the following jumper setting you can use the frequency transmitted via
the two-wire line S as the receive frequency.
Jumper 7-9 removed: frequency on input S is not used as the receive
frequency (default).
Jumper 7-9 plugged: frequency on input S is used as the receive frequency.
With the following jumper setting you can switch the transmit and receive
frequencies.
Jumpers 8-10, 1-3: the internal transmit frequency (TxCint) is used as the
transmit and receive frequency (default).
Jumpers 10-12, 1-3: the internal transmit frequency (TxCint) is used as the
transmit frequency and the internal receive frequency (RxCint) is used as the
receive frequency.
Jumpers 8-10, 3-5: the frequency transmitted via the two-wire line S is used
as the transmit and receive frequency.
Jumpers 10-12, 3-5: the frequency transmitted via the two-wire line S is
used as the transmit frequency, the internal receive frequency (RxCint) is
used as the receive frequency. With the following jumper setting you can set
the submodule for synchronous transmission with frequency control
according to the DIN draft ISO 8481. The two-wire line B (identifier X to
ISO 8481) must be switched as an output.
Jumpers 1-3, 4-6, 7-9: the internal transmit frequency (TxCint) is used as
the transmit frequency. The internal transmit frequency is simultaneously
transmitted on the two-wire line B.
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System Manual
C79000-G8576-C199-06