External J1/J2 Jumpers - Siemens A53457 Installation & Maintenance

DESCRIPTION
If J1/J2 jumper detection is disabled and the WAG is configured for RS485, the Boot Monitor
assumes that the jumpers are in place, the WAG will immediately launch the executive software,
not offering the usual boot menu.
If J1/J2 jumper detection is enabled and the Boot Monitor doesn't detect the transmitted test
frame being looped back to it, the Boot Monitor will try again, up to four more times, performing
a bit of a delay between each test.
If the Boot Monitor never sees the test frame come back to it, it decides that the J1/J2 jumpers
are not in place. The boot menu will be offered and the WAG will default to operate in RS232
mode, ignoring the fact that it's configured for RS485.
The reason for this J1/J2 jumper detection is so that the operator can unplug the RS485 multidrop
cable from the WAG, remove the J1/J2 jumpers, plug in his or her computer, and apply power on
the WAG. When the WAG determines that the jumpers are not in place, the operator can be given
a menu and can launch the executive software to reconfigure the WAG or to acquire its system
event log.
NOTE: If an operator needs to configure the WAG and it's in RS485 mode and the operator
doesn't want to open the WAG to remove the jumpers, the operator may Telnet into the WAG to
perform the configuration. The operator must know the WAG's IP address.
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EXTERNAL J1/J2 JUMPERS

The use of the J1/J2 Jumpers on the hardware can be moved off of the PC board and on to the
connector plugged into the WAG's serial interface. This way the operator need never open the
WAG to remove jumpers in the event he or she wants to access the WAG serially.
Having an RS485 Half-Duplex multidrop serial cable with pins 2 and 3 and pins 14 and 16 tied
together, performs the same electrical function of the J1/J2 internal jumpers.
When an externally jumpered cable is plugged into the WAG, the test frames that are issued by
the WAG are looped back to the WAG via the cable rather than the jumpers. When the cable
performs the tie-up of the required signals, the J1 and J2 jumpers can remain removed and RS485
Half-Duplex will continue to work properly.
The benefit of having external signal ties is that the operator may simply unplug the RS485 cable,
plug a computer into the WAG, and cycle power. With J1/J2 Jumper Auto Detect enabled, the
WAG will determine that the jumpers are not present and the operator will be given a boot menu
and from there will be able to access the WAG's configuration menus and log.
Once the operator is finished, the RS485 cable can be plugged back into the WAG and the WAG's
power would be cycled. When the WAG issues its test frames, the WAG will go back to normal
RS485 Half-Duplex operation.
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Document No.: COM-00-05-16 June 2006, Revised June 2014
Version: C.1