RS-232 to RS-485 Converter with BB-485TBLED Data LEDs, Software Driver Control Features Converts RS-232 signals to RS-485 signals Extends data communication up to 1219 meters (4000 ft) Data rate: up 115.2 kbps Quick inline installation Terminal block for easy wiring LEDs for Receive and Transmit data lines Multi-drop capability - up to 32 receivers per driver 12 Vdc power supply required (not included, sold separately) Introduction Ordering Information Overview Model No. Description Model BB-485TBLED converts unbalanced, full-duplex RS-232 signals to balanced, full or half-duplex RS-422 or RS-485 signals. RS-485 is an enhanced version of the RS- BB-485TBLED RS-232 to RS-485 Converter 422 Standard allowing multiple drivers and receivers on a two-wire or four-wire system. The RS-232 port, configured as DCE, has a female DB25 connector with pins 2 (TD Accessories Sold Separately input), 3 (RD output), and 7 (Signal Ground) supported. Pins 4 (RTS) and 5 (CTS) are tied BB-SMi6-12-V-ST power supply, 12 Vdc, 6 Watt, stripped and tinned, together, and pins 6 (DSR), 8 (CD), and 20 (DTR) are also tied together. Pins 1 (Frame international AC input, international AC blades (power supply required) Ground) and 7 (Signal Ground) are connected straight through to the RS-485 terminal blocks. The RS-485 terminal blocks support Transmit Data (A-) and (B+), Receive Data (A-) and (B+), Frame Ground, Signal Ground, and +12 VDC input. See schematic. LEDs TD & RD Proper operation of any RS-485 system requires the presence of a return path. The RS-485 Model BB-485TBLED has two LEDs: Transmit Data LED to show when the RS-485 driver Standard recommends that a third wire be used for this. For safety, a 100 Ohm resistor should is enabled and Receive Data LED showing data appearing at pin 3 of the RS-232 port. be connected between Signal Ground and the reference wire at every drop point. While it may These are useful for determining if data is getting through the converter. Note that the TD be possible to interconnect Signal Grounds directly, this is not recommended due to the danger LED indicates that the RS-485 driver is enabled. Data must be present on pin 2 of the of poissible circulating currents being present. RS-232 side for data to be transmitted out of the RS-485 side. If no data is present, no data will be transmitted even though the TD LED is illuminated. No wire type or maximum run length is listed in the RS-485 Standard. However, the RS-422 Standard (which is very similar) recommends number 24 AWG twisted-pair telephone cable Flow Control - Jumpers with a shunt capacitance of 16 picofarads per foot, and no more than 1219 meters (4000 ft) of Model BB-485TBLED uses two different methods to enable the RS-485 driver: either by distance. toggling Request to Send (pin 4) of the RS-232 side, or by automatic sensing of the data on Transmit Data (pin 2) of the RS-232 side. This option is user-selectable by setting Powering push-on jumpers located next to the terminal blocks. See Figure 1. Also, by removing Model BB-485TBLED required a 12 Vdc external power source (power supply not included, sold both sets of jumpers completely constantly enables the RS-485 driver and receiver. This separately). makes the BB-485TBLED act like an RS-422 converter. Baud Rate - Resistor 9 Resistor R9 is a timing component on the converter, see Figure 1. This resistor is part of the automatic sensing circuit and affects the baud rate at which the converter can be used in a two-wire setup. It is factory selected to run at 9600 baud or higher. With this component, the RS-485 driver will shut off approximately 1ms after the last character has been sent. If you need to change the BB-485TBLED to a baud rate other than 9600 baud, you can change this component. To change the baud rate, remove R9 and add through-hole component R14, see Table 1. Figures 2 and 3 show how to interconnect two RS-485 converters using 4-wire and 2-wire methods. The Echo jumper is used in the 2-wire mode, and allows you to prevent data being sent from the RS-232 port from being echoed back to the RS-232 port. Up to 32 receivers can be driven by any one RS-485 driver, allowing you to put together large systems with many drop points. If you are using termination resistors, they should be located at opposite ends of the system. BB-USOPTL4-2P BB-USOPTL4-4P 0221ds All product specifications are subject to change without notice. BB-485TBLED 2321dsBB-485TBLED Figure 1. R9 Resistor & Baud Rate Specifications Serial Technology RS-232 Connector DB25 female RS-485Connector Terminal block Data Rate Up to 115.2 kbps Power Source External (power supply required, not included, sold separately) Input Voltage 9 to 14 Vdc Mechanical Dimensions 54.5 x 84.34 x 18.43 mm (2.14 x 3.32 x 0.725 in) Enclosure In-line mount, plastic Environmental Operating Temperature 0 to +70 C (+32 to +158 F) Meantime Between Failures (MTBF) MTBF 1850680 hours Calculation Method MIL 217F Parts Count Reliability Prediction Table 1. Baud Rate Timeouts Regulatory Approvals / Standards / Directives Approvals FCC, CE Resistor Replacement for Changing Baud Rate Timeouts 2014/30/EU Electromagnetic Compatibility Directive Resistor R3 2011/65/EU amended by (EU) 2015/863 Reduction of Baud Rate Time (ms) CE Directives (Ohm) Hazardous Substances Directive 1200 8.33 820k 2012/19/EU Waste Electrical and Electronic Equipment (WEEE) EN 55032 Class B Electromagnetic Compatibility of 2400 4.16 430k Multimedia Equipment Emission Requirements 4800 2.08 200k CE Standards EN 55024 - Information Technology Equipment - Immuity 9600 1.04 100k Characteristics Limits and Methods of Measurement 19200 0.520 56k EN 61000-6-3 + A1 Generic Emission Standard for 38400 0.260 27k Residential, Commercial and Light-industrial Environments Standards - other (Class B) 57600 0.176 16k EN 61000-6-2 Generic Immunity Standard for Industrial 115200 0.0868 8.2k Environments Figure 2. 4-Wire RS-485 Figure 3. 2-Wire RS-485