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4 FOSTCDR2999 Manual
B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104
Table 1: RS-485 Timeout Selection
Baud Rate
Pos. 1
Pos. 2
Pos. 3
Pos. 4
Pos. 5
R9
Time(ms)
1200 ON OFF OFF OFF OFF 820 KΩ 8.20
2400 ON OFF OFF OFF OFF 430 KΩ 4.30
4800 OFF OFF OFF OFF ON
Not Used
2.20
9600 OFF OFF OFF ON OFF
Not Used
1.30
19.2K OFF OFF ON OFF OFF
Not Used
0.56
38.4K OFF ON OFF OFF OFF
Not Used
0.27
57.6K ON OFF OFF OFF OFF
Not Used
0.22
76.8K ON OFF ON ON OFF
Not Used
0.14
115.2K ON ON ON OFF OFF
Not Used
0.10
153.6K ON OFF OFF OFF OFF 6.2 KΩ 0.06
230.4K ON OFF OFF OFF OFF 4.3 KΩ 0.04
460.8K ON OFF OFF OFF OFF 2.2 KΩ 0.02
the driver could be disabled before transmission is complete, resulting
in data corruption. If the time is set too long, the RS-485 device may
respond before the RS-422/485 driver in the FOSTCDR is disabled,
corrupting this response. We recommend that the timeout be set for
approximately one character time or longer. The character times for
several different baud rates are selectable on switch positions 1
through 5. If you need a different timeout than what is provided, R10
can be removed and replaced with a different value R9. Table 1
shows the different timeout values for the switch positions as well as
some typical R9 replacement values.
Position 6 of SW1 sets the unit as a “Repeating” module or a
“Terminating” module. When the FOSTCDR is set as a “Repeating”
module, data arriving on the Fiber Optic receiver is repeated back out
the transmitter. When set as a “Terminating” module, data arriving at
the Fiber optic receiver is not sent back out the Fiber Optic
transmitter. Position 6 must be turned “On” when the FOSTCDR is to
be used as one of the Slaves in a multi-drop ring configuration. It
must be turned “Off” when the FOSTCDR is to be used as the Master
in a multi-drop configuration or as either end of a point to point
communication line. See Figure 3 for typical system setups using
the FOSTCDR in its different modes.