ABB 23WT23 PCB Modem Serial Communications

APPLICATIONS

The 23WT23 board is a modem that converts serial data according to the CCITT V.23 standard.

Therefore, it can be used for transmission over leased PTT lines, private networks or radios.

The two-wire or four-wire mode of operation can be selected via jumpers. The Voice Frequency (VF) output has a high impedance and can connect up to 10 remote stations to multiple pull-down lines.

The modem 23WT23 is available in two versions (rubrics):

- R0001: 5 VDC power supply

- R0002: 24 VDC power supply

Features

The 23WT23 circuit board is a printed circuit in Eurocard (160 mm x 100 mm) format.

All necessary configurations, such as transmit-output level, receiver sensitivity, and two- or four-wire operation, can be configured via jumpers.

The interface to the Data Terminal Equipment (DTE) operates according to the RS 232-C standard and provides the following signals:

- TxD Transmit Data

- RxD Receive Data

- RTS request to send

- DCD Data carrier detect

- CTS Clear to transmit

- DSR Data setup ready

The receiver level is monitored and the alarm relay, together with the light-emitting diode (LED) “ST”, indicates a longer (approx. 4-6 seconds) interruption of the carrier.

The LED on the front panel shows the signal status of the RS 232-C interface. The serial interface signals as well as the VFT line can be measured or opened using the disconnect test socket on the front panel.

If a higher isolation voltage is required, an additional VF signal transformer must be used.

Optionally, surge voltage protection elements can be inserted on request to protect against transient overvoltage spikes (see Figure 2).

The 23WT23 modem operates according to the CCITT V.23 standard in half and full duplex mode at 1200 bits/second.

The R002 version is compatible with the 23WT21 modem connector and can only be used in the RTU232 base subrack. In all other cases, the 5-volt version of R0001 should be used.