B&B Electronics FOSTCDR User Manual

DIN Mount Fiber Optic Converter CECE
Model FOSTCDR
Document No. FOSTCDR2999
This product Designed and Manufactured
In Ottawa, Illinois USA
of domestic and imported parts by
707 Dayton Road -- P.O. Box 1040 -- Ottawa, IL 61350 USA
Phone (815) 433-5100 -- General Fax (815) 433-5105
Home Page: www.bb-elec.com
Sales e-mail: sales@bb-elec.com -- Fax (815) 433-5109
Technical Support e-mail: support@bb.elec.com -- Fax (815) 433-5104
© Copyright 1999 B&B Electronics -- August 1999
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B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104
Table of Contents
DESCRIPTION.................................................................................................1
RS-232 CONNECTIONS ...............................................................................1
RS-422 & RS-485 CONNECTIONS............................................................1
FIBER OPTIC CONNECTIONS ...................................................................2
DIP-SWITCH SETUP......................................................................................3
MULTI-DROP OPERATION.........................................................................5
SPECIFICATIONS ..........................................................................................6
FOSTCDR DIAGRAM....................................................................................7
FOSTCDR2999 Manual Table of Contents i
B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104
Description
The FOSTCDR is designed to provide the most versatile connection possible between any asynchronous serial equipment using Fiber Optic cable. It allows any two pieces of asynchronous serial equipment to communicate full or half-duplex over two fibers at typical distances up to 2.5 miles. The converter can also be set up in "Repeater" mode to create a multi-drop master/slave configuration, allowing one serial device to talk to multiple slave devices around a fiber ring. The DIN rail mountable box makes it ideal for industrial cabinets and enclosures.
RS-232 data signals up to 115.2K bps and RS-422, or RS-485 data signals up to 460K bps are supported. Different standards can be mixed and matched to allow RS-232 devices to connect to your RS-422 or RS-485 system. This means the FOSTCDR can replace converters and isolators when connecting remote devices, while providing the EMI/RFI and transient immunity of optical fiber.
The FOSTCDR supports both the Transmit and Receive data lines, and provides full hardware control of the RS-422/485 driver with B&B's Automatic Send Data Control circuit. Timeouts are dip-switch selectable between 0.10 and 2.2 ms. All serial connections are provided on terminal blocks, while the multi-mode fiber is connected via two ST connectors. The unit is powered by 10 to 30VDC at 140 mA max.
RS-232 Connections
Connection of the FOSTCDR is simple and straightforward. The RS-232 driver and receiver are connected to 2 terminal blocks. The RS-232 DATA OUT is on terminal block (A), and the RS-232 DATA IN is on terminal block (D). Ground is located on terminal block (B) and (C), and power comes in on terminal block (F).
RS-422 & RS-485 Connections
The RS-422/485 driver and receiver are connected to 4 terminal blocks. Signal ground is on terminal block (M), and power comes in on terminal block (J). When connecting to a four-wire RS-422/485 device or system, connect the output of your device to terminal block (L) (RDB or RD+) and terminal block (K) (RDA or RD+). Connect the input to your device to terminal block (H) (TDB or TD+) and terminal block (G) (TDA or TD-). For two-wire RS-485 systems, the driver and
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receiver of the FOSTCDR must be connected together by tying terminal blocks (L) and (H) together and (G) and (K) together. This allows the FOSTCDR to communicate half-duplex over the same pair. Refer to Figure 1 for connection diagrams to your RS-422 or RS-485 equipment.
Figure 1: RS-422/485 Connection Diagrams
422/485 4W Device
FOSTCDR
485 2 Wire Device
FOSTCDR
TD A (-) TD B (+) (L) RD B
RD B (+)
(K) RD A
(G) TD ARD A (-)
(H) TD B
(M)GND
Data A (-)
Data B (+)
(K) RD A
(L) RD B (G) TD A
(H) TD B
(M)GND
If termination is needed, the PCBD is laid out to allow a termination resistor (Rt) to be soldered in across the RD(A) and RD(B) lines. Removing R8 and R16 and replacing them with through­hole components can also change the off-state bias resistor values. Before making modifications to the FOSTCDR, be sure to consult B&B Electronics’ free RS-422/485 Application Note or other sources of information to see if termination is necessary. The Application Note is available from our Web site, or call and we will happily send you one at no charge.
Fiber Optic Connections
The FOSTCDR uses a separate LED emitter and photo-detector operating at 820 nm wavelength. Connections to the emitter and detector are on ST type connectors. Most multi-mode glass fiber size can be used including 50/125 µm, 62.5/125 µm, 100/140 µm, and 200 µm. One fiber is required for each connection between a transmitter and receiver. In a point to point configuration, two fibers are required between the two modems, one for data in each direction. A multi-drop ring configuration requires one fiber between TX and RX around the loop. See Figure 2 for typical point to point and multi-drop configurations.
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The most important consideration in planning the fiber optic link is the “power budget” of the fiber modem. This value represents the amount of loss in dB that can be present in the link between the two modems before the units fail to perform properly. This value includes line attenuation as well as connector loss. For the FOSTCDR the typical connector to connector power budget is 12.1 dB. Because
62.5/125 µm cable typically has a line attenuation of 3 dB per Km at 820 nm, the 12.1 dB power budget translates into 2.5 miles. This assumes no extra connectors or splices in the link. Each extra connection would typically add 0.5 dB of loss, reducing the possible distance by 166 m (547 ft.). The actual loss should be measured before assuming distances.
Figure 2: Typical Setups
Point to Point
RS-232 RS-422
or RS-485
Device
or System
Full Duplex
RS-232 RS-422
or RS-485
Device
or System
FOSTCDR
SW1:6 = OFF SW1:6 = OFF
TX
RX
Duplex
Multimode
Fiber
RX
TX
Multi-Drop Ring
TX
FOSTCDR
SW1:6 = OFF
MASTER
Multimode
RX
Fiber
SLAVE
TX
SW1:6 = ON
FOSTCDR
RS-232 RS-422
or RS-485
Device
or System
RX
SLAVE
FOSTCDR
TX
SW1:6 = ON
FOSTCDR
RS-232 RS-422
or RS-485
Device
or System
RX
or RS-485 or System
SLAVE
RS-232 RS-422
Device
TX
SW1:6 = ON
FOSTCDR
RS-232 RS-422
or RS-485
Device
or System
Dip-Switch Setup
The Dip-Switch (SW1) on the FOSTCDR defines the mode of operation when being used for RS-422 or RS-485. Positions 1 through 5 on the switch determine the timeout of the RS-485 driver. Because the driver is controlled by hardware, a specific time must be set to tell the hardware how long to wait for data on the fiber side before turning off the RS-422/485 driver. If this time is set too short,
RX
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Pos. 1
Pos. 2
Pos. 3
Pos. 4
Pos. 5
Time(ms)
Not Used
Not Used
Not Used
Not Used
Not Used
Not Used
Not Used
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.
Table 1: RS-485 Timeout Selection
Baud Rate
1200 ON OFF OFF OFF OFF 820 K 8.20 2400 ON OFF OFF OFF OFF 430 K 4.30 4800 OFF OFF OFF OFF ON 9600 OFF OFF OFF ON OFF
19.2K OFF OFF ON OFF OFF
38.4K OFF ON OFF OFF OFF
57.6K ON OFF OFF OFF OFF
76.8K ON OFF ON ON OFF
115.2K ON ON ON OFF OFF
153.6K ON OFF OFF OFF OFF 6.2 K 0.06
230.4K ON OFF OFF OFF OFF 4.3 K 0.04
460.8K ON OFF OFF OFF OFF 2.2 K 0.02
R9
2.20
1.30
0.56
0.27
0.22
0.14
0.10
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.
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(full duplex)
Positions 7 and 8 of SW1 determine when the RS-422/485 driver and receiver are enabled. Position 7 controls the driver and Position 8 controls the receiver. For RS-422 operation, set both switches to the “Off” position. For multi-drop RS-485 four-wire systems, position 7 should be “On” and position 8 should be “Off.” This allows the receiver to be enabled all of the time and eliminates some possible timing problems. For RS-485 two-wire systems, both switches should be in the “On” position. This disables the RS-422/485 receiver whenever the driver is enabled, preventing data from being echoed back to the fiber side of the FOSTCDR. Table 2 illustrates the switch settings for typical setups.
Table 2: 422/485 Switch Settings
RS-485 2-Wire Mode
(half duplex)
RS-485 4-Wire Mode
(full duplex)
RS-422 Mode
Position 7
TX Enable
ON ON
ON OFF
OFF OFF
Position 8
RX Enable
Multi-Drop Operation
A multi-drop configuration can be created by forming a ring of FOSTCDRs. Each transmitter is tied to the following converter’s receiver, starting at a master node and continuing around to each slave and back to the master. By setting SW1:6 to the “On” position on the slaves, all data sent from the master or preceding slaves is echoed back out the fiber transmitter to the rest of the slaves and eventually back to the master node.
Because all data is echoed back, there are special considerations when constructing a multi-drop system. The master will see its own transmitted data. This means that the master device must be full-duplex (RS-232, RS-422, or four-wire RS-485) and that it must be capable of ignoring or otherwise accepting its own echoed transmission. Slaves must also be able to accept data from previous slaves in the loop.
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B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104
Specifications
Transmission Line: Dual multi-mode optical cable Point to Point Transmission: Asynchronous, half or full-duplex Multi-Drop Transmission: Asynch., half duplex, master/slave, ring Interfaces: RS-232, RS-422, or RS-485 Data Rates : 0 to 115.2K bps RS-232; 0 to 460K bps RS-422/485 Typical Range: Up to 2.5 miles (4.0 km) on multi-mode glass fiber Coupled Power Budget: 12.1 dB Optic Wavelength: 820 nm Connectors: Terminal blocks/serial connection, ST connectors/fiber Power Supply: Requires 10 – 30 VDC @ 140 mA max. Temperature Range: -20°C to 80°C Dimensions: 4.4”L x 3.0”W x 1.0”H (11.2 x 7.6 x 2.5 cm)
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FOSTCDR Diagram
Figure 3: FOSTCDR Circuit Diagram
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FEDERAL COMMUNICATIONS COMMISSION RADIO FREQUENCY INTERFACE STATEMENT
Class A Equipment
This equipment has been tested and found to comply with the limits for Class A digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. Operation of this equipment in a residential area is likely to cause harmful interference, in which case the user will be required to correct the interference at personal expense.
FCC Class A Equipment Statement
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