3.10 Protection/ Redundancy definition

The IO-FEP2 provides up to 16 instances of automatic 1:1 protection / redundancy switching units. Each protection switch controls the waveguide switch with the same number. With this page the operation mode of each protection switch and it's alarm input assignment is configured.

Operation Mode

Each protection switch may be configured to one of the following operation modes:

• UNUSED --- The protection switch is not configured
• 1:1-SW-ONCE --- The protection switch is configured for '1:1 switch once' mode
• 1:1-SW-ALWAYS --- The protection switch is configured for '1:1 switch always' mode
• 2:1-SW-ONCE --- The protection switch (and it's neighbour) are coupled and used to build a switch once 2:1 chain redundancy circuit.

To configure a protection switch it's required, first to configure the waveguide switch controlled by this protection switch instance at the Setup / WG Switches page. Protection switches belonging to "UNUSED" waveguide switches are marked with "n/a" and cannot be configured.

Input Assignment

For each protection switch configured as 1:1-SW-ONCE/1:1-SW-ALWAYS up to 5 alarm inputs for chain A and up to 5 alarm inputs for chain B may be assigned. It is not required to configure all 5 fault inputs for a chain, unused inputs are marked with "none". Obviously, at least one alarm input for each chain must be configured to make the 1:1 protection work.

Chain A is defined as the equipment chain which is selected while the waveguide switch is in position A, chain A faults are fault signals originated by equipment in chain A, hence causing the protection switch to switch over to position B. How fault inputs are assigned for 2:1 protection switches, see below.

Only inputs configured as ALARM inputs may be selected as a fault input signal for a protection switch. Hence, the inputs must be configured at the Setup / Input Circuits page before they can be used in a protection switch.

1:1-SW-ONCE vs. 1:1-SW-ALWAYS Operation

A protection switch toggles it's position if there is no fault at the actually redundant chain and there is at least one fault at the actually selected chain. Thereby the software honours any signal inversion or delay configured for each individual input. Switching to the redundant chain causes the protection switch to set the SWITCHED flag as an indication that a switchover took place. In 1:1-SW-ONCE mode, this prevents the protection switch from switching back to the original position until the SWITCHED flag has been reset by the operator. In 1:1-SW-ALWAYS mode the protection may switch back if the switching condition appears laterally reversed.

2:1-SW-ONCE 2:1 Chain Operation

This mode lets you couple two consecutive protection switch units to build one 2:1 chain redundancy switch. If you select this mode, the following assignments / prerequisites apply:

1. Each switch controls one operational chain with switch position A meaning "the chain is in use". Position B switches the redundant chain in place. This means switch positions A/A describe the normal operation mode, A/B or B/A appear if the redundant chain has been switched in place of one of the operational chains. The switch combination B/B usually makes no sense.
2. The chain A fault inputs of each switch are to receive faults from the corresponding operational chain. All chain B fault inputs are combined (logical OR), receiving faults from the redundant chain.
3. A 2:1 redundancy unit switches the redundant chain in place of an operational chain if it is enabled, if there is no fault pending for the redundant chain. A 2:1 redundancy is only active in "NONE" position, therefore acts in a "switch once" manner.