RS-485 Interfaces
This page lists RS-485 devices that connect to a PC, either by converting to RS-232, or via USB and other interface.
RS-485 USB Interfaces
The following interfaces provide RS-485 through a USB connected device. These generally create a virtual COM port under Windows.
B&B Electronics: USPTL4
- Tested with WattNode Modbus
- Non-isolated
- 15kV ESD
- 4.7k internal bias resistors
- Note: Set all four DIP switches to "ON" position to disable echo and select 2-wire RS485 interface
- WattNode Modbus meter's A-/B+ can be wired to either TDA/TDB or RDA/RDB.
SerialComm: Model USB-485B
- Non-isolated
SerialGear: USB-COM-I
- Isolated
SerialGear: USB-COMi-M
- Tested with WattNode Modbus
- Not isolated
- 15kV ESD
- Built-in 120 ohm termination resistor
- Built-in 750 ohm bias resistors
- Connect WattNode Modbus terminal A- to adapter terminal 1 (next to the corner); terminal B+ to terminal 2; and terminal C to terminal 6 (next to the USB connector).
- The DIP switches should be S1=ON, S2=OFF, S3=OFF and S4=OFF for Half Duplex, 2-wire operation without Echo.
- For reliable operation in the presence of industrial EMI sources and where long bus lines are used, it is recommended to use bus biasing and termination. To enable these, open the metal case and install jumper 1-2 (120 ohm Tx termination), jumper 3-4 (750 ohm Tx+ pull-up) and jumper 5-6 (750 ohm Tx- pull-down). The remaining jumpers may be left in the storage position as shipped from the factory.
Sealevel: SeaLINK+485I
- Fully isolated
Sealevel: SeaLINK+485
- Same as SeaLINK+485I but without isolation
Quatech: QSU2-400
http://www.quatech.com/catalog/usb_2.0.php
ICP DAS: I-7561
- 3000V isolation
ICP DAS: I-7563
- 3000V isolation
- Three RS485 ports
B&B: USOPTL4
- Tested with WattNode Modbus
- Optically isolated
- 15kV ESD
- 4.7k internal bias resistors
- Set all four DIP switches to "ON" position.
- Note: Does NOT work with terminated networks unless two bias resistors are replaced with different values, requiring soldering!
ByteRunners' Serial Gear Clones
- USB-COMi-M and USB-COMi-SI-M (isolated)
US Converters' USB to RS-485/422 Mini
- 600W surge protection, 15KV static electricity protection
- Terminal block
US Converters' USB to RS-485/422 Converter
- 600W surge protection, 15KV static electricity protection
Moxa: UPort 1130
- Software selectable support for both two-wire and four-wire RS-485
- Not isolated
- 15KV ESD
- Comes with mini-DB9F-to-terminal block adapter
RS-485 to RS-232 Converters
RS-232 to RS-485 conversion is tricky and not recommended for new applications. A terminated RS-485 bus requires 60mA of drive current, but port-powered RS-232 adapters cannot provide this much current, so unless the adapter is powered with an external supply, these will not work with terminated or heavily loaded buses. Some vendors of this type are listed below.
- [B&B 485SD9TB, $79] Works for bench testing but is not adequate for production use. Does not support termination. Poor drive.
- [B&B model 485PTBR Port Powered] Works with Campbell logger.
- Integrity Instruments
- CommFront
RS-485 to Ethernet Interfaces
Moxa NPort 5130
- Tested with WattNode Modbus
- http://www.moxa.com/product/NPort_5130.htm - Moxa, DB-9, UL, CE, FCC Class A, includes jumper-selectable 1K or 150K pull-up/pull-down resistors. Moxa also makes a DB9M to terminal block adapter (which avoids the need for soldering to a mating DB9F connector), called the MiniDB9FTB, and the pin-out of this is the same as for the Moxa UPort 1100 USB/RS485 adapter.
- http://www.neteon.net/Product/125-134-105-448-387/Vendors-MOXA-NPort-ExternalModels-NPort5130#order
- http://www.neteon.net/srch.aspx?w=MiniDB9FT
Lantronix UDS1100
- Tested with WattNode Modbus
- http://www.lantronix.com/device-networking/external-device-servers/uds1100-iap.html Lantronix UDS1100 $149 from Mouser. Ethernet to RS232/422/485
- [1] - Lantronix embedded converters
- [2] - UDS-1100, UL, DB-25 connector
- [3] - Lantronix standalone converters
Miscellaneous Brands/Models
- http://www.lantronix.com/device-networking/external-device-servers/xpress-dr_dr-iap.html - UL, CE, etc.
- http://www.sealevel.com/product_detail.asp?product_id=745&Ethernet_to_RS_422_RS_485_Serial_Server_ 4102 Optoisolated.
- http://www.usconverters.com/index.php?main_page=product_info&cPath=66&products_id=190 BF430 Has terminal block for RS485. Requires 9VDC adapter.
- http://www.easysync-ltd.com/ ES-E-1001-M RS485
- http://www.perle.com/products/IOLAN-DS-Terminal-Server.shtml This adapter has TrueSerial technology for low latency serial connections and specifically says it will work as a Modbus gateway: http://www.perle.com/Supportfiles/TrueSerial.shtml , UL,
- http://www.neteon.net/Product/340-3-13-366/Serial-SerialtoEthernet-1Port-GW215 Neteon. DB9. No termination or bias. Has LEDs. 5 VDC or 24 VDC. Requires AD15-24C power supply.
- http://aaxeon.com/s.nl/it.A/id.192/.f?sc=7&category=902 Aaxeaon STE-501C DB9. No termination or bias. LEDs. DB9 for RS485. Terminal block for 5 VDC or 9-30 VDC
- http://www.provantage.com/startech-netrs2321e~7STR90KT.htm StarTech NETRS2321E includes 9 VDC supply. Terminal block. No termination or bias. Has LEDs.
- http://www.digi.com/products/serialservers/digiconnectsp.jsp Very compact.
Control Solutions, Inc. Minnesota
They sell the Babel Buster line of converters for converting among Modbus RTU, Modbus TCP, BACnet, LonWorks, SNMP, etc.
- Babel Buster SPX - Modbus TCP - RTU, SNMP
EZE System, Inc.
They sell an Ethernet to Modbus adapter/controller as well as an EzeIO Metering kit that bundles a CCS Modbus WattNode meter and CT's with their device, which also offers GSM connectivity. http://ezesys.com/products/product-list.html
Virtual Ethernet COM Port Drivers
There are several programs available that make virtual COM ports. These can be used to get a Modbus signal converted back from Ethernet into a COM port so that Modbus software could access the packets as Modbus RTU.
- http://www.hw-group.com/products/hw_vsp/index_en.html - free for a single COM port, connects to a TCP connection.
- http://www.digi.com/products/serialservers/digiconnectsp.jsp
RS485 to WLAN Interfaces
- http://www.moxa.com/product/NPort%C2%AE_W2150_2250_Plus.htm The Moxa W2150 Plus is a 1-port RS232/422/485 IEEE 802.11a/b/g wireless device server that supports WEP, WPA and WPA2 encryption and roaming between several APs (Access Points).
- http://www.neteon.net/Product/340-177-348-576/Serial-SerialtoWireless-802.11abg-NPortW2150+#order
See Also
Keywords: RS-485 adaptor
