CHAPTER 3: WIRING
B3000-B Serial Brains User’s Guide
13
Wiring a B3000-B to a SNAP-PAC-S2 Controller
NOTE: The SNAP-PAC-S2 supports both two-wire and four-wire RS-485. Use PAC Manager to configure the serial
ports. For details, see form 1704, the
PAC Manager User’s Guide
.
Two-wire
Two-wire with interrupt line
Pin 1
Earth GND
TX/RX +
TX/RX –
COM
TX/RX +
TX/RX –
COM
TX/RX +
TX/RX –
COM
Middle of cable
All switches OFF
1
2
3
ON
1
2
3
ON
Termination switches, end of cable
IRQ and TX/RX ON; RX OFF
Configure serial port as
2-wire 485 with
termination and bias
Pin 1
Earth GND
TX/RX +
TX/RX –
COM
TX/RX +
TX/RX –
COM
TX/RX +
TX/RX –
COM
Middle of cable
All switches OFF
1
2
3
ON
1
2
3
ON
Termination switches, end of cable
IRQ and TX/RX ON; RX OFF
IRQ +
IRQ –
IRQ +
IRQ –
Configure serial port as
2-wire 485 with
termination and bias
