line of Data Acquisition and Control Boards, you should remove the resistor networks on all the RS485 stations but the last one).
The data lines are protected by 4 diodes and 2 Zeners each, which prevent voltages over 6 Volts from reaching the drivers.
CONNECTION TO THE COMPUTER:
The RS232/RS485 Converter has a 9 pin DB9 connector of which only 3 lines are used: TX, RX and Ground. The Converter is connected to the computer with a serial cable through the DB9 connector to the target computer’s serial port. Commercial serial cables can have either ‘straight’ data lines or ‘crossed’ (null modern) data lines.
In order to accommodate both types of cables, jumpers H1 and H2 are provided to allow for either a ‘straight’ or a ‘crossed’ connection to the TX and RX lines. If a ‘straight’ cable is used, jumper H1 is set on RX and H2 on TX. If a ‘crossed’ cable is used, jumper H1 must be set on TX and H2 is set on RX. No RTS or other control lines are used since the link is fully duplex.
Figure 2.
3