2-15
2
2.7.2.2 RS-485 Connections
The 2363 has two RS-485 signals on Pins 14 and 16 for a half-duplex RS-
485 connection. Pin 14 has the Tx/Rx+ signal; pin 16 has the Tx/Rx- signal.
The 2363 contains an internal network termination circuit with 1 Kohm
pullup and pulldown resistors and a 220 ohm termination resistor. The
termination network biases J1 pin 16 at 2.44 Vdc and pin 14 at 2.2 Vdc.
Half-duplex RS-485 networks normally have only one termination network
in or close to the last device on the network. Long networks may have a
termination network at both ends of the network cable. To remove an
unwanted 2363 Termination Network, open the 2363, unsolder and remove
resistors R5, R6 and R7 from the PC board. These resistors are located near
the front of the PC board between the PWR and RDY LEDs.
The 2363’s RS-485 port can be tested by using a RS-232 to RS-485
converter to connect the 2363 to a PC’s COM port The recommended
converter is a MA485F25 from ICSDataCom.com. Figure 2-5 shows the
connections from the PC to the 2363. Use a plain pin-to-pin cable from the
PC to the MA485F25 Converter. Use ICS’s SERkybd program (see para
3.9.7) of an equivalent program to test the network protocols.
2363 Parallel Interface
ICS
Electronics
DC
PWR
PC
RS-232
MA485F25
RS-232 to RS-485
Converter
2363
RS-485
Lines
Notes:
Wiring List
MA485F25 Terminals 4 & 5 to 2363 J1 pin 14
MA485F25 Terminals 3 & 6 to 2363 J1 pin 16
MA485F25 Terminal 7 to blk/wht wire (+ Vdc)
MA485F25 Terminal 8 to blk wire (GND)
Figure 2-5 2363 RS-485 Test Connections
