Instructions

Description of the SHDSL permanent line modem
104275_en_c00 PHOENIX CONTACT 1-11
1.6.3 Star structure (for all interfaces)
Figure 1-7 Star structure (RS-232, RS-422, RS-485)
The star structure in the example (Figure 1-7) consists of three modems. It is a line structure
where the middle modem has been moved up to act as the head station. This means that
two SHDSL ports are available at each modem.
In mixed operation with an RS-232 device and an RS-422 or RS-485 device, hardware or
software handshake is not supported.
In the case of RS-422 and RS-485, there are no cables designed for hardware hand-
shake. This is therefore not supported.
There is no defined general software handshake for RS-232, RS-422, and RS-485. This
is therefore not supported either.
You can implement a line structure in which full and half duplex interfaces are used (e.g.,
RS-485 and RS-232/RS-422). In this case, however, the protocol must ensure that all in-
terfaces are operated in half duplex mode.
If a line structure is created with just full duplex-compatible interfaces (RS-232, RS-422),
the protocol must ensure half duplex mode.
RS-232 and RS-422 interfaces are usually designed for a point-to-point connection and
not a line structure.
RS-232
RS-422
RS-485
RS-232
RS-422
RS-485
RS-232
RS-422
RS-485
Half duplex
Table 1-3 Information on the interfaces
Interface basics Connection to the SHDSL modem (connector pin
assignment)
RS-232 See "RS-232" on page 1-6 See "RS-232 interface" on page 2-10
RS-422 See "RS-422" on page 1-7 See "RS-485 W2/RS-422 interface" on page 2-11
RS-485 W2 See "RS-485 W2" on page 1-8