Transcript
A Sierra Monitor Company
ENOTE 0074 Using the B&B 4850TLED RS-232 to RS-485 converter
Rev 7
TABLE OF CONTENTS 1
Using the B&B Electronics 485OTLED with a FieldServer ................................................................................ 2 1.1 General Considerations: ................................................................................................................................2 1.2 Converting FieldServer RS-485 to RS-232 ......................................................................................................2 1.3 Converting FieldServer RS-232 to RS-485 ......................................................................................................4
ENOTE 0074 Using_the_B&B_4850TLED_RS-232_to_RS-485_converter Rev 7
1
USING THE B&B ELECTRONICS 485OTLED WITH A FIELDSERVER
The 485OTLED is an optically isolated RS-485 to RS-232 converter which can be used to convert a FieldServer RS232 port to RS-485, or a FieldServer RS-485 port to RS-232. The reasons for doing this are application specific, therefore this application note will merely focus on how to set this device up for FieldServer connection, and what to consider for the remote serial device being connected on the other side of the 485OTLED.
1.1
General Considerations:
BAUD Rate:
CONTROL: TERMINATION:
1.2
The BAUD rate must be the same on the RS-232 side as it is on the RS-485 side. This also applies to parity and data bit settings. The chosen baud rate must be set on the 485OTLED using dip switches 1-4. The 4850TLED supports a wide range of BAUD rates, but it is recommended that the BAUD be set to 38400 or below to reduce noise problems. The RS-485 communications can be driven either by communications detection (SD) or by the RTS pin. Use SD when the FieldServer is the RS-232 device. If the 485OTLED is the last RS-485 device on the network, set dip switch 8 to ON, otherwise it needs to be off.
Converting FieldServer RS-485 to RS-232
The diagram below shows the connection information for making this conversion. Please remember that Rx of the 485OTLED goes to Tx of the Remote Serial Device, and vice versa. Use an RS-232 mini tester to verify good connection if needed.
FieldServer Technologies 1991 Tarob Court Milpitas, California 95035 USA Web: www.fieldserver.com Tel: (408) 262 2299 Fax: (408) 262 2269 Toll Free: (888) 509 1970 email:
[email protected] Page 2 of 4
ENOTE 0074 Using_the_B&B_4850TLED_RS-232_to_RS-485_converter Rev 7 Connector Legend SMC p/ n 91035, Mfg. by B & 485 OTLED. Switch Settings : Baud ECHO ON 2 WIRE TERM
Refer to Table1 5 ON 6, 7 ON 8 OFF*
Tx
3
Tx
RTS
5
RTS
3 4
GND GND
RS- 232 TO RS- 422/485 OPTICALLY ISOLATED CONVERTER
2
7
RS-232
2
SR-422/485
Rx
Rx
Recceive
Transmit
B& B electronics MODEL485 OTLED
J2
7
2
3
4
5
6
7
8
TB1 TDA(-) TDB(+) RDA(-) RDB(+) 422/ 485 GND TB2 +12V R- 232 GND
DB25F Note: Pins4& 5 and pins6,8& 20 are bridged internally to allow for RS - 232 devices that need hardware control .
O N 1
SD RTS
RS- 232 Device
JP1
4800 9600 19.2K 38.4K ECHO 4W/2W 4W/2W TERM.
* ON if last device in RS - 485 network only
FieldServer
91035 R 1 or R2 + (B) - (A) GND +
NOTES: 1
EARTH GROUND: )
1
GND
By Factory Field Wiring
10-30VDC Power Supply
CONNECTION DIAGRAM FOR CONVERTING FIELDSERVER RS - 485 TO RS- 232 USING MODEL4850 TLED CONVERTOR Sheet 1 of 2 BASE NAME: M 4301-10-4. VSD
DATE : 7/27/06
FILE NAME: 450TLED. VSD
BY : MC
REV . 1
Table 1: Switch settings for commonly used baud rates Baud 1200 9600 19200 38400
Switch 1 OFF OFF OFF OFF
Switch 2 OFF ON OFF OFF
Switch 3 OFF OFF ON OFF
Switch 4 OFF OFF OFF ON
R 21 820kÙ Not Used Not Used Not Used
Time out (ms) 9 1.1 0.6 0.3
FieldServer Technologies 1991 Tarob Court Milpitas, California 95035 USA Web: www.fieldserver.com Tel: (408) 262 2299 Fax: (408) 262 2269 Toll Free: (888) 509 1970 email:
[email protected] Page 3 of 4
ENOTE 0074 Using_the_B&B_4850TLED_RS-232_to_RS-485_converter Rev 7
1.3
Converting FieldServer RS-232 to RS-485
The diagram below shows the connection information for making this conversion. It is important to know in this application whether the remote serial device is 2-wire or 4-wire RS-485, and then to make the correct wiring connections and set dip switches 5, 6 and 7 accordingly. Connector Legend SMC p/ n 91035, Mfg. by B & B Electronics Model 485 OTLED. Switch Settings : Baud ECHO ON 2 WIRE TERM
Refer to Table1 5 ON 6, 7 ON 8 OFF*
FS- 8915-10 * ON if last device in RS - 485 network only
FieldServer
3 4
5 7
7
RS- 232 TO RS- 422/ 485 OPTICALLY ISOLATED CONVERTER Recceive
Transmit
B& B electronics
JP1
O N 1
2
3
4
5
6
7
8
TB1 TDA(-) TDB(+) RDA(-) RDB(+) 422/ 485 GND
MODEL485 OTLED +12V R-232 GND
J2 DB25F 21787
TDA(-) TDB (+) RDB(+) RDA(-) GND
SD RTS
2
3
SR-422/485
2
RS-232
FS-8917-01
4800 9600 19.2K 38.4K ECHO 4W/2W 4W/2W TERM.
Remote Serial Device– 4 wire
TB2
Remote Serial Device– 2 wire
91035
NOTES: 1
EARTH GROUND: COPPER WIRE OR BRAIDED CABLE MADE SPECIFICALLY FOR GROUNDING PURPOSES )
+ (B) - (A) GND
+
By Factory Field Wiring
2
GND
10-30VDC Power Supply
CONNECTION DIAGRAM FOR CONVERTING FIELDSERVER RS - 232 TO RS- 485 USING MODEL4850 TLED CONVERTOR Sheet 1 of 2 BASE NAME: M 4301-10-4. VSD
DATE : 7/27/06
FILE NAME: 450TLED. VSD
BY : MC
REV . 1
Table 2: RS-485 settings for Remote Serial Device Communication Mode RS-422 Mode (full duplex) RS-485 4-Wire Mode (full duplex) RS-485 2-Wire Mode (half duplex)
JP1 Neither RTS or SD RTS or SD
Switch 5 Echo OFF OFF ON
Switch 6 4W/2W OFF OFF ON
Switch 7 4W/2W OFF OFF ON
FieldServer Technologies 1991 Tarob Court Milpitas, California 95035 USA Web: www.fieldserver.com Tel: (408) 262 2299 Fax: (408) 262 2269 Toll Free: (888) 509 1970 email:
[email protected] Page 4 of 4
