The TU849 is a module termination unit (MTU) for redundant
configuration of Optical ModuleBus Modem TB840/TB840A.
The MTU is a passive unit having connections for double power
supply, one for each modem, a single electrical ModuleBus, two
TB840/TB840A and a rotary switch for cluster address (1 to 7)
setting.
Four mechanical keys, two for each position, are used to
configured the MTU for the right types of modules. Each key has six
positions, which gives a total number of 36 different
configurations. The configurations can be changed with a
screwdriver.
The MTU can be mounted on a standard DIN rail. It has a
mechanical latch that locks the MTU to the DIN rail. The latch can
be locked/unlocked with a screwdriver.