Optical Systems OSD1250 User manual

OPERATOR MANUAL
OSD1250
SELF HEALING RING
DUPLEX DATA TRANSCEIVER

OPTICAL SYSTEMS DESIGN
OSD1250 OPERATOR MANUAL
PAGE 3
DOC ID: 10106110
INDEX 1
1TECHNICAL SUMMARY...........................................................................................................................4
1.1 DESCRIPTION ...........................................................................................................................................4
1.2 APPLICATIONS..............................................................................................................................................4
1.3 FEATURES AND BENEFITS ............................................................................................................................4
1.4 TYPICAL DESIGN APPLICATION ....................................................................................................................5
1.5 THEORY OF OPERATION........................................................................................................................5
1.6 FRAME STRUCTURE................................................................................................................................7
1.7 SPECIFICATIONS......................................................................................................................................8
2INSTALLATION AND OPERATING INSTRUCTIONS.........................................................................9
2.1 DRAWINGS AND MOUNTING DIMENSIONS.......................................................................................9
2.2 SWITCH SETTINGS ................................................................................................................................10
2.3 POWER IN CONNECTION.......................................................................................................................10
2.4 DATA I/O CONNECTION ........................................................................................................................11
2.5 ALARMS .....................................................................................................................................................12
2.7 FIBER OPTIC CABLE CONNECTION.....................................................................................................12
2.8 OPTICAL POWER LEVELS.....................................................................................................................13
2.9 OSD1250 INDICATORS ..........................................................................................................................14
3MAINTENANCE.........................................................................................................................................16
3.1 EXTERNAL INSPECTION ......................................................................................................................16
3.2 ROUTINE MAINTENANCE....................................................................................................................16
4WARRANTY ...............................................................................................................................................17
4.1 WARRANTY PERIOD .............................................................................................................................17
4.2 REPAIRS...................................................................................................................................................17
4.2.2 WARRANTY REPAIRS...................................................................................................................17
4.2.2 OUT-OF-WARRANTY REPAIRS...................................................................................................17
4.2.3 SITE REPAIRS..................................................................................................................................17
4.2.4 EXCLUSIONS...................................................................................................................................17
FIGURE 1: BASIC BLOCK DIAGRAM.................................................................................................6
FIGURE 2: MOUNTING DIMENTIONS ...............................................................................................9
FIGURE 3: POWER IN CONNECTION...............................................................................................10
FIGURE 4: CONTACT CLOSURE OUTPUT ......................................................................................12
FIGURE 5: LED FRONT PANEL INDICATORS. ...............................................................................14
FIGURE 6: BUS CONFIGURED SYSTEM..........................................................................................15
FIGURE 7: RING CONFIGURED SYSTEM........................................................................................15
TABLE 1: OSD1250 SPECIFICATIONS................................................................................................8
TABLE 2: SWITCH SETTINGS ...........................................................................................................10
TABLE 3: DATA I/O CONNECTION..................................................................................................11
TABLE 4: LED INDICATOR FUNCTIONS ........................................................................................14

OPTICAL SYSTEMS DESIGN
OSD1250 OPERATOR MANUAL
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DOC ID: 10106110
1TECHNICAL SUMMARY
1.1 DESCRIPTION
The OSD1250 is a small, self-contained optical modem designed to interconnect Bus Master/Slave Data Terminal Equipment
either in bus or ring topologies using dedicated optical fibers. Data link networks of hundreds of kilometres can be achieved
when using singlemode fiber, with a maximum spacing between optical modems of 30km. Polled Data protocols are normally
used to determine data traffic flow and will only be limited by the propagation timing throughout the network.
The OSD1250 has data interfaces for RS232, RS422, RS485 (2 wire), and RS485 (4 wire). Anti-streaming logic, which is set
to 300ms detection time, prevents a faulty data transmission from hogging the network. The anti-streaming logic can be turned
off for RS232 and RS422 thus allowing very low data rate or DC level to be transmitted.
This system operates by sampling the incoming data from one of the data interface at a high rate, encoding it and transmitting
over the fiber. Each subsequent modem simply regenerates this encoded signal so that pulse distortion does not depend on the
number of units in series. Consequently, an OSD1250 based system can have as many modems in series as required to cover
all likely situations.
Each OSD1250 within a network monitors the status of adjacent units to determine the ‘health’ of the network. This
information is used to determine the default data traffic direction. The direction will automatically be changed if necessary in a
redundant ring when a network fault occurs.
The OSD1250 card is designed to mount in the OSD350N or OSD370N chassis. The OSD1250C is designed to mount on a flat
surface .The OSD1250 operates from an unregulated DC supply of +12 to 24VDC @ 6VA.
1.2 APPLICATIONS
Industrial networks using RS422 or RS485 based
programmable logic controllers
Transportation communications
Access control systems
Fire and alarm systems
Building automation
1.3 FEATURES AND BENEFITS
2 and 4-wire RS485, RS422, or RS232 operation
Extends module separation to several kilometres
of multimode fiber and to over a hundred
kilometres of singlemode fiber
Compatible with all common fiber sizes
Available in redundant Ring and Bus
configurations
Complete end-to-end isolation with up to 40 units
In series
DIN rails or surface mounting
Built-in test features
Safe transmission in hazardous environments
Immune to electrical interference
Extremely robust electronics and packaging
designed for severe industrial environments
Full duplex, asynchronous, DC to 2Mbps
Powered by non-critical 9 to 30VDC supplies

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DOC ID: 10106110
1.4 TYPICAL DESIGN APPLICATION
1.5 THEORY OF OPERATION
A simplified block diagram of the OSD1250 is shown in Figure 1.
The unit is designed to operate either in bus or ring topologies (see Figure 5 & Figure 6).
In all cases only one unit in the network is designated the Bus Master and acts as both the start and end of the bus/ring, i.e.
signals do not pass through from Channel 1 to Channel 2 (and vice versa) as they do at the slaves.
In the case of a bus topology, the unit(s) located at the extremities of the system require only one Channel: the unused Channel
is fitted with protective caps. Note that the Bus Master unit does not have to be at the extremity of the bus.
A further consideration is the need to ensure that faults don't cause the bus to be monopolised. This could be due to a software
fault in a remote unit causing transmission or it may be a fault within the optical modem forcing a logical "l" to be
continuously transmitted. The unit therefore has three anti-streaming (or anti-jabber) circuits, which inhibit transmission if the
preset time limit of 300ms is exceeded and then enable transmission after the streaming signal is removed. The OSD1250
removes a streaming signal for a minimum of 1 second. This ensures that a faulty unit cannot monopolise the bus for more than
30% of the time. The OSD1250 does not require any special settings for user data rates from 300bps to 2Mbps (25% distortion
max). The OSD1250 is best suited to polled data protocols.
A concern with systems like this which continuously regenerate the signals is that system timing can be lost or degraded if an
intermediate unit fails. The OSD1250 overcomes this by having a fixed crystal oscillator at each node. When the incoming data
exhibits either a very high bit error rate (this rate is around 1x 10-2), or the incoming optical signal is lost, the associated
transmitter’s timing is switched over to the fixed oscillator and the receiver recovered clock is also stabilised with the fixed
oscillator.
BUS CONFIGURATION
OSD1250
1 or 2fibers 1 or 2fibers
OSD1250
OSD1250
RS232 / RS422 / RS485 RS232 / RS422 / RS485 RS232 / RS422 / RS485
RING CONFIGURATION
OSD1250
1 or 2fibers
OSD1250
RS232 / RS422 / RS485 RS232 / RS422 / RS485
1 or 2fibers

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OSD1250 OPERATOR MANUAL
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DOC ID: 10106110
FIGURE 1: BASIC BLOCK DIAGRAM

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DOC ID: 10106110
The primary method of managing data traffic is the use of RTS/DCD. In RS232 and RS422, the RTS signal envelopes the user
data. In RS485, a voltage ‘window’ comparator is used to detect when the copper pair is driven out of the idle state. The output
of window comparator is used to provide a pseudo RTS signal. The RTS signal is used to enable data buffers at the remote end
as DCD.
The OSD1250 data interface is via a high density DB26 female connector. Essential modem control signals are available as
RS232 or RS422 signals. Translation between RS232 and RS422 is possible. The OSD1250 generates Data Set Ready only
when it detects the adjacent units are in their correct operating state. The OSD1250 does use Data Terminal Ready as true input
to determine if DTE is operational. If user hardware does not use DSR/DTR then a wire link should be used between these 2
signals on the interface connector.
Data received from the fiber is sent to the receiver outputs and tri-stated or continuously driven depending on each mode.
Output signals from the interface like DSR are only ‘true’ if the OSD1250 links are operational,
The Net Error signal has been included to indicate a Link failure. It can be used to energise a relay for normal operation. A
network or power failure will cause a relay to be de-energised. The maximum rating for relay is 30V at 100ma.
The receivers will deliver the correct idle logic state output without any signals connected at inputs. MOV and diode protection
is included on all outputs.
1.6 FRAME STRUCTURE
The simplest and most robust way of transmitting the data over the fiber is to encode it using methods like Bi-phase or
Manchester coding. This enables simple and effective timing recovery and bit error monitoring over the link..
The OSD1250 uses a 32MHz primary clock. The data is transmitted as manchester encoded data at 16Mbps. The high speed
sampling of user data is at 8Mbps. The remaining 8Mbps is further divided into a 4Mbps channel for sampling RTS and 8
channels each at 0.5Mbps. The 0.5Mbps channels are used for synchronisation, network status bits, and three low speed data
channels.
The frame is multiplexed such that user data is sampled every second bit. Every second alternate bit is RTS/DCD. The
remaining bits reflect the 8 channels at 0.5Mbps.

OPTICAL SYSTEMS DESIGN
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DOC ID: 10106110
1.7 SPECIFICATIONS
SPECIFICATION
PERFORMANCE
Electrical
Data Interface
RS232,RS422,RS485 2 WIRE, RS485 4 WIRE
Electrical Connector
HDB26
Data Rate
DC to 2Mbps
Bit Error Rate
< 1 x 10-9
Alarms
Network Failure
Alarm Interface
Open drain MOSFET rates at 200mA @ 50V max
Optical
Optical Wavelength
1300nm (850nm and 1550nm are optional)
Optical Connectors
ST Standard
Transmit Power
-12 to -6dBm
Receive Sensitivity
< -35dBm
Receive Saturation
> -5dBm
Receiver Fail Indication
< -39dBm to –41dBm
Indicators
Copper Transmit Data Present
Amber (1 Only)
Receiver Optical Signal Ok
Green/Red (2, 1 per port)
Receiver Sync Ok
Green/Red (2, 1 per port)
Laser Ok
Green/Red (2, 1 per port)
Receiver Data Present
Amber (2, 1 per port)
Receiver Bit Error
Red (2, 1 per port)
Transmitter Switched to Local Crystal
Red (2, 1 per port)
Packaging and Environmental
Dimensions (mm) excluding flanges and connectors
104W x 144D x 40H (Module)
128W x 142D x 50H (Card)
Weight
350g (card), 500g (module)
Operating Temperature
-20C to 70C
Relative Humidity
0 to 95% non-condensing
Power Requirements
+9 to 30VDC @ 6VA
102125005
TABLE 1: OSD1250 SPECIFICATIONS

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OSD1250 OPERATOR MANUAL
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DOC ID: 10106110
2INSTALLATION AND OPERATING INSTRUCTIONS
This section briefly outlines the steps required to install and operate the OSD1250 successfully. It should be studied carefully
to avoid undue damage to the equipment and poor operation.
This equipment has been fully tested before dispatch and is ready for immediate operation. However, it is advisable to check
for external transportation damage before operation. If damage is present, return the unit and packing to the supplier
immediately.
2.1 DRAWINGS AND MOUNTING DIMENSIONS
The unit is designed to rest on a flat surface such as a modem tray or bench top or, via the optional mounting bracket onto a
TS32 DIN rail. The card versions are designed to be inserted into a chassis and secured by means of captivated screws.
FIGURE 2: MOUNTING DIMENTIONS
4.2
8.5
DETAIL 'A'
6.6
128
111
144
109
40
128
142
50

OPTICAL SYSTEMS DESIGN
OSD1250 OPERATOR MANUAL
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DOC ID: 10106110
2.2 SWITCH SETTINGS
In the context of the following switch settings for the module version the ON position is UP and the OFF position is down.
The term AS refers to Anti-Streaming.
The BIAS switch SW2 is dual function and only generates BIAS in RS485 modes.
MODE
SW1
SW2
SW3
SW4
RS485 BIAS
MASTER
ON
SLAVE
OFF
RS232 WITH AS
OFF
OFF
OFF
RS422 WITH AS
OFF
OFF
OFF
RS232/422 NO AS
ON
ON
OFF
RS485 2 WIRE
AS REQUIRED
ON
ON
RS485 4 WIRE
AS REQUIRED
OFF
ON
TABLE 2: SWITCH SETTINGS
2.3 POWER IN CONNECTION
Units are powered by +9V to 30VDC @ 6VA.
FIGURE 3: POWER IN CONNECTION
WARNING - Ensure that you are using the correct voltage!
The unit employs an internal resetable solid state fuse to protect both it and the power source in the event of a fault in the
modem’s internal power supply.
The OSD1250 card version requires DC power which is connected via a DB9 connector and supplied by the OSD370N or
OSD350N chassis. The card should be fixed into the chassis using the captivated screws. The cards can be plugged in or out of
the chassis with power on or off.
1
2
3
4
5
6
7
8
9
10
11
12
13
A
B
C
D
E
Negative Input
Positive Input