TB100 Terminal Block Adaptor
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The TB100 Terminal Block Adaptor attaches to the DB9M serial port connector. The TB100 provides a convenient way of attaching wires in RS422 and RS485 systems. The wires are inserted into the terminal contacts and the terminals are then tightened using a screwdriver.
The following table details terminal block contact functions in case the terminal block is connected to the DS100:
As explained in serial port pin assignment the DS100B supports half-duplex RS485 communications, but the RX and TX line pairs on the DB9M connector of the DS100B are separated. In order to arrange a half-duplex two-wire RS485 bus you need to externally connect RX+ to TX+ and RX- to TX-. On the TB100 this is conveniently done by closing (putting to ON position) two switches- SW1 and SW2- located on the back of the TB100.
Additionally, the TB100 provides termination circuits typically needed at the end of the RS422 or RS485 bus. There are four identical terminators that can be switched on individually using switches located on the back of the TB100. The following table details which line pairs the terminators can be connected to:
Schematic diagram for one of the terminators is shown on figure below.
Notice, that if you are using RS485 half-duplex mode (SW1 and SW2 are closed) and you want to terminate the RS485 bus, then you only need to close either SW5 or SW6. Having both switches closed will effectively add two termination circuits to the bus!