Baud Rates - GE F485 Instruction Manual

Configuration

Baud rates

F485 COMMUNICATIONS CONVERTER – INSTRUCTION MANUAL
The converter box is configured via two internal dip switch banks which are accessible by
removing the converter box cover. Switches A1-A8 are used to set the baud rate for RS485
communications and determine whether the converter is DTE (RS232 direct) or DCE (RS232
modem). Switches B1-B6 are used to select the interface type. The designator for each
switch is clearly marked on the printed circuit board. The tables shown provide a
description of each switch within the switch banks.
Table 1: Switch A (baud rates)
BAUD A1 A2 A3
1200 ON OFF OFF
2400 OFF ON OFF
4800 OFF OFF ON
9600 OFF OFF OFF
19200 OFF OFF OFF
38400 OFF OFF OFF
57600 OFF OFF OFF
Table 2: Switch A (DTE/DCE)
MODE A8
DTE OFF
DCE ON
Table 3: Switch B (configuration)
CONFIGURATION B1
RS232 TO RS485 OFF
RS232 TO FIBER OFF
RS485 TO FIBER ON
Two-wire RS485 is half duplex and requires a means for switching between a receive or
transmit state. The F485 converter uses the incoming data to control the direction and
therefore requires no control signals from the master device (RS232 or fiber) to switch from
transmit to receive mode after the last character has been transmitted. The baud rate
switches control the length of time that the RS485 transmitter will remain in the transmit
direction after the last character has been transmitted. The length of time is fixed at 3.5
character times at the selected baud rate making it suitable for use with Modbus® RTU
protocol. When converting RS232 to FIBER, these switches (A1-7) have no effect.
A4 A5 A6
OFF OFF OFF
OFF OFF OFF
OFF OFF OFF
ON OFF OFF
OFF ON OFF
OFF OFF ON
OFF OFF OFF
B2 B3 B4 B5
ON OFF ON OFF
OFF OFF OFF ON
OFF ON OFF OFF
A7
OFF
OFF
OFF
OFF
OFF
OFF
ON
B6
OFF
ON
OFF
5