User's Guide

The Hardware View SB300 Series
Page 100 Proprietary and Confidential 2110059 Rev 1.1
11.4.7. SB220 Modem Conneciton
This is provided for factory testing of older model modems not detailed in this manual.
11.5. Jumpers
There are five jumper blocks provided on the MIB. Two of these are for the SB220, which is not
covered in this document. The three blocks used with the SB300 Series modems are summarized
below and discussed in detail in following sections.
The main jumper block is located next to the modem power switch and has eight pairs of pins.
When the jumper is connected it has these functions.
• ST IN1 Activate the input signals (not currently implement
• ST IN2 on the modems).
• ST IN3
• ST IN4
• \SHDN Activate the \SHDN signal to the modem.
• HOSTSHDN Enable the \SHDN signal from the SB301/302 host connector.
• TP CTRL Enable test point TP5.
• MODEM DIS Disable the RS-232 serial connection from the modem.
There is also a 3-pin jumper block for power selection. A jumper MUST connect the centre
pin (2) to one of the outside pins (1 or 3) to enable power to the modem.
• 1 – 2 MIB power is used.
• 2 – 3 Host power (SB301/302 host connector) is used.
A 2-pin jumper block is available to enable or disable the built-in speaker. When the jumper is
connected, the speaker is enabled.
11.5.1. Main Jumper Block
The main jumper block (J24) has eight pairs of pins, all labelled. The first four pairs are to
activate the four input signals of the SB320 (not currently implemented by the modem). Two
pairs are for direct MIB activation of the Shutdown (\SHDN) signal to the modems and to enable
the SB302 host interface to trigger this signal. There is one pair of pins for activating TP5 and the
last pair is to disable the modem side of the RS-232 / HCMOS serial signal conversion.
11.5.1.1. ST INx – Status Inputs
Placing a jumper on one of these pins will force the signal active. At this time none of the status
input signals are used by the SB320 or SB300.
11.5.1.2. \SHDN – Shutdown
This jumper forces the modem’s Shutdown (\SHDN) input active (low). Placing a jumper on this
pair of pins forces the signal on. This will work regardless of the jumper setting of the host
shutdown enable.
11.5.1.3. HOSTSHDN – Host Shutdown Enable
This jumper enables the Shutdown (\SHDN) signal from the host side interface to be passed to the
modem. Without the jumper installed, the signal will not reach the modem. This jumper does not
activate the signal; only allow the signal from the host connector to be passed to the modem.
If the host side connector is not being used, this jumper should be left open (not connected). This
will prevent a floating signal from the host connector block from reaching the modem.
This jumper is independent of the forced-shutdown jumper (\SHDN).