Nitek FRS58111xR00 - Manual (Page 3)

Low Speed Data Operation
Data Channel A
Channel A allows for RS232, RS422 (full duplex, four wire) or RS485 (half duplex, two wire) interface depending
on the position of the switch located above the RJ45 connector. The switch signifies the presence of a
RS232/422/485 Data Interface Board. If there are LEDs on the RJ45 connector an Ethernet Interface Board is
present.
The data input for both the RS485 and the RS422 modes detects a tri-state input condition by monitoring the
differential voltage level across the input. A differential level below 120mV will be detected as a tri-state
condition. A level above 120mV will be detected as a logic 1 or logic zero. It is important to terminate the
RS485 or RS422 input using 120 ohms if a pre-bias is present on the RS485 or RS422 input. A large
number of third party equipment manufacturers apply a pre-bias on their RS485 bus. This pre-bias is applied by
pulling one side of the RS485 bus high (+5 volts) and the other side low (0 volts) using high value resistors within
the third party equipment. In order to ensure that the NITEK equipment detects a tri-state condition, these
resistors should have a value above 5k ohm. If the third party bias resistors are less than 5k ohm the bus can be
double or triple terminated as required to ensure that a tri-state level is detected.
Data Channel B
Channel B interface is only present on a unit if an ACX Interface Board is installed. This data interface board can
be any one of the following:
Safety
The 5000 series of products uses a Class 1 laser system in accordance with IEC 60825-2.
It is always advisable to follow good practices when working with optical fiber systems. This includes:
•
Do not stare with unprotected eyes at fiber ends or connector faces.
• Use only approved filtered or attenuating viewing devices.
• For other safety issues and advice on good practices associated with optical fiber systems see IEC 60825-2
or your local safety officer.
0 No Interface
1 RS422/RS485
2 RS232
3 Audio
4 Contact Closure TX/RX
5 2 Contact Closures TX
6 20mA
7 TTL Data
8 FTT10A
Option Description
ACX Interface Options