9.534 Protection-Switch-1-To-1-Dual

The Protection-Switch-1-To-1-Dual logical device provides a software based solution for a 1:1 symmetric redundancy switch. The devices knows two basic modes called "SINGLE" and "DUAL". Although designed to switch between two redundant Antennas, the device may be used in other environments as well.

SINGLE mode

In SINGLE mode the device knows one active and one redundant antenna (or e.g. transmit chain) which is in stand-by state. When the active side becomes faulty and the stand-by side shows no fault, the devices switches over to the other side. This works symmetrically, there is no preferred side for the device. Depending on the SW-ONCE/SW-ALWAYS setup parameter, the device locks switching after it switched once until the operator releases this by clicking the RESET button (SW-ONCE). In SW-ALWAYS mode, the device will switch back to the original side if the the switchover condition appears in the opposite sense.

When used with two Antennas, the SINGLE mode is used if all RX- and TX- signals are routed through the active antenna only. The stand-by Antenna is not in use.

DUAL mode

This mode is used with two antennas, which are used at the same time (load sharing). In case of a fault on one side, all signals used with this antenna are routed through the other one. The device does not check a "location" input signalling which antenna actually is in use.

Fault monitoring

The logical device monitors the fault states of a couple of devices, deriving from this the information whether to switch over. Actually the device supports five fault flags for each chain which are logically ORed to obtain the chain fault.

Delay pararameters

The Protection-Switch-1-To-1-Dual logical device provides two delay parameters which control the device's behaviour in different situations.

• Switchdelay --- This delay controls the time, a fault condition must be present before the device switches from primary to backup
• Recoverydelay --- If the device switches to backup, the primary chain states OK again and a fault happens at the backup chain, the device switches back to the primary chain after this time. This delay prevents the redundancy switch from oscillating if the switch over process itself causes a short fault at the backup chain.

All delay values may be set to zero resulting in an immediate reaction of the device.

Device window pages

The following table shows which device window pages are available with this individual device type. Tool-bar functions not mentioned here are described at the general description of device windows .

• --- This page controls the operational parameters of the device.
• --- The faults page.
• --- The device info page.
• --- The maintenance page. The configuration parameters described below are set at this page.

Configuration parameters

At the maintenance page of the device window there are a couple of configuration parameter which must be set to interconnect the redundancy switch with the devices it shall monitor and control.

Fault definitions

The Protection-Switch-1-To-1-Dual device defines a couple of individual faults to report the device's actual state. The fault conditions always are shown as LEDs at the first page if the device window. Depending on the individual fault configuration, these conditions also may be logged and summarized to a device fault for the redundancy switch. The table below describes the fault flags defined for the Protection-Switch-1-To-1-Dual device.

• Single Fault --- Becomes true if at least one of the configured fault inputs becomes true. This also means that -- if the switch over already has occurred -- the protection switch actually is not able to compensate a possible fault in the remaining chain. Enable this fault if you want to be warned in this case.
• Double Fault --- In each chain at least one device reports a fault. The (transmit-) facility probably is not operable in this case.
• Path Select Switch --- This flag simply maps to the fault selected with the 'switchFaultId' configuration variable.
• Protection --- The protection switch raises (and latches) this fault flag if a switch over occurs. This fault maps to the 'switched' LED at the user interface. The flag is reset if you apply a 'RESET' command to the device (this command does nothing else for the Protection-Switch-1-To-1 device. Enable this fault if you want the switch over to be signaled as a latched fault.
• Invalid location --- This fault becomes active when the location detection neither reports the "side 1" location nor the "side 2" location. In a configuration with two antennas this will probably mean that not all switches are set properly to route all signals via antenna 1 or antenna 2.

Variables defined by this device driver