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Manual
Distributed Smart Switch
Model 485DSS
Documentation Number 485DSS-0308
This product
Designed and Manufactured
In Ottawa, Illinois
USA
of domestic and imported parts by
B&B Electronics Mfg. Co. Inc.
707 Dayton Road -- P.O. Box 1040 -- Ottawa, IL 61350
PH (815) 433-5100 -- FAX (815) 433-5105
Internet:
http://www.bb-elec.com
orders@bb-elec.com
support@bb.elec.com
© 1998 B&B Electronics -- January 2008
485DSS-0308 Manual
Cover Page
B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104
B&B Electronics – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph +353 91 792444 – Fax +353 91 792445
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Table of Contents
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Summary of Contents for B&B Electronics 485DSS
- Page 1 Distributed Smart Switch Model 485DSS Documentation Number 485DSS-0308 This product Designed and Manufactured In Ottawa, Illinois of domestic and imported parts by B&B Electronics Mfg. Co. Inc. 707 Dayton Road -- P.O. Box 1040 -- Ottawa, IL 61350 PH (815) 433-5100 -- FAX (815) 433-5105 Internet: http://www.bb-elec.com...
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Page 3: Table Of Contents
ISTRIBUTED MART WITCH OMMANDS The Command String ... 10 ON Command ... 10 OFF Command ... 11 STATUS REQUEST Command ... 11 485DSS A ... 14 ETTING THE DDRESS Table 4. Address Switch ... 14 ... 15 INARY RANSFER CHAPTER 2: SOFTWARE ... 16 ... - Page 4 HART ONNECTOR TO 485DSS RS-232 (DTE) P ... C-1 3. RS-232 DCE D /DB25 C HART EVICE W 485DSS RS-232 (DTE) P ... C-1 2. IBM PC DB9 C HART ONNECTOR TO 485DSS RS-232 (DTE) P ... C-1 4. RS-232 DCE D...
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Page 5: Chapter 1: Hardware
The RS-485 Distributed Smart Switch (485DSS) connects one RS-232 device to an RS-485 multi-node network as shown in Figure 1. To accomplish this, the 485DSS converts RS-232 to an addressable RS-485 node. A unique address, from 0 to 255, is user assigned by setting switches on the 485DSS. -
Page 6: Specifications
Figure 2. Top View of Circuit Board Port Configuration The 485DSS has a RS-485/422 port and a RS-232 port. The RS-485/422 signals are on terminal blocks. Table 1 shows you the pinouts and Figure 2 shows you the location of the terminal blocks. -
Page 7: Rs-232 Port
2. IBM PC's are DTE devices and modems are DCE devices. Only TD and RD of the RS-232 port pass through to the RS-485 port when the 485DSS is ON. The 485DSS raises and lowers the RTS output signal on the RS-232 port to reflect the connect state of the port. -
Page 8: Rs-422/485 Wiring
Host, the microcontroller will automatically enable the driver before transmitting the first character of the reply and disable the driver after the last character of the reply. When the 485DSS is ON (selected) and the RS-232 device is transmitting data to the Host the Send Data (SD) control circuit enables and disables the driver. -
Page 9: Table 3. Component Values For Send Data Timing
Table 3 into the R21 position. Use Figure 2 to locate R15 and C10. NOTE: The SD timing circuit does not control the RS-485 driver when the 485DSS sends reply messages to the host. Table 3. Component Values For Send Data Timing... -
Page 10: 4-Wire Mode
Figure 2 for the jumper location. In this position on a 4-wire network the Host and the RS-232 device can communicate in full duplex. CAUTION: Data loss may occur if the Host sends 485DSS commands while the host is receiving data from the network! 485DSS-0308 Manual B&B Electronics Mfg Co Inc –... -
Page 11: Figure 4. Rs-422 Wiring Diagram
B&B Electronics’ free RS-422/485 Application Note. Power Supply The 485DSS requires an unregulated DC power source that will supply +12 volts at 100 milliamps. Connect the positive side of the power source to the +12VDC terminal block and the common side of the power source to the GND terminal block. -
Page 12: Operation
485DSS on the network by sending them command messages. These commands can turn a 485DSS on or off, and can also request status from an individual or from all of the 485DSS's on the network. The communication setup used to send and receive these commands are: 9600 baud, 8 data bits, no parity, and 1 stop bit. -
Page 13: Figure 5. Simplified Functional Diagram
HOST can reset its communication format to match the format of the RS-232 device attached to the 485DSS. ALL data is passed through the unit after it has been selected. The 485DSS does not have any buffering. Distributed Smart Switch Commands The 485DSS constantly monitors the serial data received on the RS-485/422 port for a command string. -
Page 14: The Command String
"X-off" (decimal 19). The second and third characters represent the hexadecimal address of an individual 485DSS. The address range is from 0 to 255 (HEX "00" to "FF"). Some commands require the use of the broadcast character "DC2"... -
Page 15: Off Command
RS-232 device is requesting access to the network and if it has access to the network. By using this command the Host has the ability to prioritize all the 485DSS's on the network. A specific address in the address field specifies a 485DSS-0308 Manual B&B Electronics Mfg Co Inc –... - Page 16 485DSS's on the network. This command temporarily turns off (disconnect) the RS-232 port from the network while transmitting the reply message. The reply message transmitted by the 485DSS consists of six ASCII characters. The first character is the acknowledge character, an upper case "A"...
- Page 17 Example: A unit with a decimal address of ten will have a delay of 220 milliseconds [(10 x 0.02) + 0.02 = 0.22 seconds]. Command character: ACK (decimal 6) Example 1: To request status from the 485DSS set to address 11 ( 0B hex) decimal. HOST transmits: Xoff “0”...
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Page 18: Setting The 485Dss Address
To access this switch, you will need to remove the top cover of the 485DSS. Insert a small screwdriver in the slot in the side of the cover and twist to remove it. Each switch position is equal to a specific weight value. -
Page 19: Binary File Transfer
When transmitting binary files through the Distributed Smart Switch, it is possible that a string of characters could resemble a 485DSS command message. If this would happen, there could be a disruption in the transfer process and a loss of data. A simple solution to this problem is to change to a different baud rate before transferring binary files. -
Page 20: Chapter 2: Software
The Distributed Smart Switch Demonstration (DSS_DEMO) Program (IBM PC or Compatible) provides the user with examples of how to receive and transmit commands to the 485DSS. The DSS_DEMO.EXE is a DOS executable program written in QuickBasic that will send turn on, turn off, and status request commands to the 485DSS. - Page 21 ^ ctrl _ 485DSS-0308 Manual B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104 B&B Electronics – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph +353 91 792444 – Fax +353 91 792445 “...
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Page 23: Appendix B: Decimal/Hexadecimal Conversions
Decimal Value 485DSS-0308 Manual B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104 B&B Electronics – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph +353 91 792444 – Fax +353 91 792445... - Page 24 B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104 B&B Electronics – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph +353 91 792444 – Fax +353 91 792445 4096 4348 (1st Hex digit) (2nd Hex digit) (3rd Hex digit) (4th Hex digit) 485DSS-0308 Manual...
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Page 25: Appendix C: Cable Charts
Appendix C: Cable Charts These charts indicate some common cable wiring based on the 485DSS RS-232 and RS-485/422 ports. Refer to the Port Configuration section of this manual for more information. Chart 1. IBM PC DB25 Connector to 485DSS RS-232 (DTE) Port... - Page 26 485DSS RS-232 (DTE) Port RS-232 DCE Serial Port Signal DB9 Connector Direction -----------> <----------- <---------> <----------- -----------> Chart 5. RS-422/485 4-Wire Device to 485DSS RS-422/485 Port. RS-422/485 4-Wire Signal Device Direction TD (A)(-) -----------> TD (B)(+) -----------> Signal Ground <---------->...