The 23WT21 modem is a CCITT V.23 modem.V.23operates with the frequency shift keyeing method.
lt allows to operate in a multi-drop network by switch-ing off the carrier.
The23WT21 modemisone of the standard modemsused for RTU560 stations.
Slot 77/81 in the basic.subrack is prepared (reserved) for the 23WT21 mo-demfor adirectconnectiontothe NFKinterface oftheCommunication unit.Themodem can also be placedin any other l/O slot.
Central part of the 23WT21 modem is a V.23 modemcircuit. Baudrate, operation mode etc.is configuredby the DlP switch register S1.
23WT21 modem supplies the CCITT V.23 standardfor:
--1200 Bd
--600 Bd
--75 Bd
--1200/75 Bd
--600/75 Bd
The 23WT21 modem is constructed to be used in RTU560stationsandinl23stations.
To run RTU560 mode set S1-1 and S1-2 to RTU560operation mode (Table 1:).23WT21 operates onlyin this position within the RTU560.
It is not allowed to plug the 23WT21 modem into anI/0 slotifS1-1(2)isset to ON(RTU560 peripheralbusproblems).