Rexroth Tightening System 300 Controls The tightening controllers, SE311 and SE312, control and monitor the tightening process, carry out the system diagnostics and monitor all individual components of a tightening channel. Tightening processes and rework strategies are simply and flexibly programmed using the BS300 software. Automatic recognition of individual components enables fast and secure start-up. The use in multi-channel systems requires a KE310 communication unit. The SE312 for single-channel applications has two unoccupied card-slots where interface modules for communication with overriding controllers can be inserted.