The MD2 modem can be used as a dedicated-line modem independently of the SINAUT ST7 system. Due to its design and the electrical properties, the MD2 is especially suited for use in the industrial sector.

Examples of use outside the SINAUT ST7 system:

• Extension of Profibus and MPI links;
  see FAQ 23671172 (for PB) or 23671640 (for MPI)
• As leased line modem for S7-200;
  see Micro Automation Set MAS 17

The MD2 enables distances of up to 33 km (at 1200 bit/s), 27 km (at 2400 bit/s) and up to 11 km (at 9600 and 19,200 bit/s) to be spanned without amplifiers/repeaters (guide values for uncoiled communication cable of type 2 x 2 x 0.8 J-Y(St)Y). By interconnecting two MD2 modems to a repeater, the specified distances can be extended several times.

The MD2 modem permits the construction of network structures in the "point-to-point", "star" or "linear" configurations, as well as combinations of these basic structures. If the modem is used in the control center, a small star network comprising two 2-wire cables can be connected at the modem output. By connecting several MD2s (max. 32) by means of their RS485 interfaces, the star network can be expanded to a multiple of 2 x 2-wire.

For the arrangement of an MD2 along a line, the modem output can be switched to high impedance. This reduces the insertion loss to a minimum and thus only marginally reduces the maximal bridgeable distance. The very short transmitter make-times ensure a prompt execution of the data traffic with the "polling" used in the dedicated line network.

Apart from private dedicated lines, the MD2 can also be connected to Telekom leased lines. Corresponding approval exists. In the case of exclusively analog leased lines, the transmission rates 1200 and 2400 bit/s are possible, whereas for analog/digital-converted leased lines the speed is usually limited to 1200 bit/s for technical reasons.

The MD2 is also ideal for data transmission via a walkie-talkie with modem input. In order to switch the walkie-talkie on and off via its PTT input, a floating optical relay is integrated in the MD2 modem that is linked with the RTS signal of the RS232 interface. The two connections of the optical relay are available on the RJ12 socket.

As walkie-talkies usually only transmit voice signals in the 300 to 3000 Hz frequency range, the transmission rate with the MD2 modem is limited here to 1200 bit/s. For 2400 bit/s, the frequency range would have to exceed 3300 Hz.