Black Box IC171C manual EIA-530

CHAPTER 4: Option Selection

Header E3 is used to control the RS-485 enable/disable functions for the receiver circuit. The RS-485 “Echo” is the result of connecting the board’s receiver inputs to the transmitter outputs. Every time a character is transmitted it is also received by the board. This can be beneficial if your software can handle it (using received characters to throttle the transmitter), or it can confuse your system if your software cannot handle it. The RS422/485 Serial Interface Plus provides a jumper block (E3) to enable or disable this function.

RX

AUTO RTS 422

Figure 4-7. This should follow the selection made at E5 if “No Echo” is desired. If Echo suppression is not desired, then leave the jumper in the “422” position. The modem control outputs are only valid when Header E3 is in the 422 mode.

AUTO	Receiver automatically Enabled/Disabled
RTS	Receiver Enabled by UART RTS signal

422Receiver always Enabled

Figure 4-8. Header E3.

EIA-530 SIO-485

Figure 4-9. DIP Shunt E4 (EIA-530 Mode).

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