NOVUS RS485 Industrial Digital Converter Instruction Manual
- June 4, 2024
- Novus
Table of Contents
NOVUS RS485 Industrial Digital Converter
SAFETY ALERTS
The symbols below are used in the device and throughout this manual to draw the user’s attention to important information related to device safety and use.
| CAUTION | CAUTION OR HAZARD | ATTENTION |
|---|---|---|
| Read the manual fully before installing and operating the device. | Risk of | |
| electric shock. | Material sensitive to static charge. Check precautions before |
handling.
All safety recommendations appearing in this manual must be followed to ensure personal safety and prevent damage to the instrument or system. If the instrument is used in a manner other than that specified in this manual, the device’s safety protections may not be effective.
PRESENTATION
USB-i485 Converter is a cost-effective way to convert RS485 or RS422
industrial buses to a USB interface. By connecting the USB-i485 Converter to a
computer USB port, it will be automatically detected and installed as a native
COM port, compatible with any existing serial communication application.
Multiple converters can be installed when using USB hubs, allowing you to
easily set up a multi-serial system without any worries about IRQ or DMA
settings.
1500 Vdc galvanic isolation between the USB port and RS485/RS422 protects the
computer from spikes or possible misconnections in the communication bus.
USB-i485 Converter can be configured for RS422, 4-wire RS485 (Full Duplex), or
2-wire RS485 (Half Duplex) networks. When operating in 2-wire RS485, the data
transfer control is automatically controlled by the converter. Two 2-wire
RS485 networks can be connected to the converter, thus duplicating the
possible number of remote devices.
DIMENSIONS
USB-i485 Converter has the following dimensions:
USB DRIVER INSTALLATION
The installation steps shown may vary from computer to computer or even between operating system versions. The steps shown below are guidelines only.
WINDOWS
- Run the driver file available on our website.
- Connect the converter to the computer USB port. Windows will detect the new hardware and automatically try to proceed with the installation.
- After a few seconds, an installation error message will be displayed on the bottom right corner of the screen. This error is because Windows does not recognize any drivers that have not been previously registered with Microsoft.
- Open the Device Manager screen and search for the “F232R USB UART” device in the “Other Devices” category. Double-click it and click on the “Update Driver…” button.
- Choose the “Browse my computer for driver software” option.
- Select the “Drivers\Windows” folder. Leave the “Include subfolders” option checked.
- After a few moments, a window will appear, asking if you want to install this device software. Select the “Install” option.
- Wait a few more seconds. A window displaying the installation success will be shown.
- ftdi_sio (specific driver of the converter);
- usbserial (generic driver for USB-Serial conversion);
- usbcore (basic driver for USB devices).
MAC
See the documentation on the device page of our website. The Virtual Driver COM file provides information about how to perform the installation.
SERIAL PORT (COM PORT) ASSIGNMENT – WINDOWS
DETERMINATION
The serial port associated to the USB-i485 Converter is automatically
determined by the operational system a few moments after the device is
connected. By accessing the Windows Device Manager, you can identify or change
the COM port associated with the USB-i485 Converter:
Control Panel → System → Hardware → Device Manager → COM & LPT Ports
You can also open the Device Manager by running the following command:
“devmgmt.msc”.
After opening the Device Manager, you can check the Serial Port (COM)
associated to the USB-i485 Converter. As it can be seen in the figure below,
the USB-i485 Converter is associated to COM7:
Figure 2 – COM Port Determination
SELECTION
If you need to change the Serial Port (COM) associated with the USB-i485
Converter, select the “USB Serial Port (COM X)” of the USB-i485 Converter. Go
to “Action/Properties” and, on the “Port Settings” tab, click on Advanced, as
shown in Figure 03. If this tab does not appear, it means that the driver was
not installed correctly. Therefore, you will need to reinstall the
configurator software.
In the “Advanced Settings for COMX” window, change the “COM Port Number”
parameter to the desired COM, as shown in Figure 04. Some serial ports may be
marked as “In Use”. Only select one of these ports if you are sure that it is
not in use by another computer device.
In some situations, serial ports may be marked as in use even when the
associated device is no longer installed on the computer. In this case it is
safe to associate them to the USB-i485 Converter.
IMPORTANT RECOMMENDATION
To improve the USB interface communication, it is recommended to configure the
“Latency Timer”. This parameter can be modified by accessing the “Advanced
Settings for COMX” window, as shown in Figure 03.
Afterwards, you can check, as shown in Figure 04, the “Latency Timer (ms)”
parameter, which must be changed to 4:
CONNECTIONS
The appropriate connection to the USB-i485 Converter depends on the type of
serial network: RS422, 2-wire RS485 or 4-wire RS485. The following figure
shows a description of all USB-i485 Converter connection terminals: 
Figure 5 – Device Connections
A shielded twisted-pairs cable is recommended for wiring the communication bus
from the converter to all network devices. The shield should be grounded
and/or connected to the common terminals of all devices. The minimum
recommended wire gauge is 24 AWG (0,2 mm2).
It is highly recommended that you use an additional conductor to interconnect
the common terminal of the network devices.
If this recommendation is not followed, communication circuits of one or more
devices on the network may be damaged. RS485 or RS422 devices from different
vendors or of different models may identify the communication terminals using
distinct notation. The following table shows some of this notations and its
equivalence to the USB-i485 Converter.
| USB-i485 CONNECTION IDENTIFICATION | Rx+ ou Tx+ | Rx- ou Tx- |
|---|---|---|
| POPULAR RS485 AND RS422 CONNECTION IDENTIFICATION | D | D |
| D1 | D0 | |
| B | A | |
| D+ | D- |
Table 1 – Identification
RS485 HALF DUPLEX (2-WIRE)
To set this mode of operation, the MOD terminal (pin 4) must be left
unconnected.
This is the usual RS485 connection. A single twisted pair is used for data
transmission and reception. Multiple RS485 devices are connected in a single
bus, as shown in the next figure. Devices from different vendors may use
different names for the data signal terminals.
In the following figure, different identification schemes are presented for
each device, with the proper connection to the USB-i485 Converter. RS485
devices can be connected to either bus 1 or 2.
Figure 6 – Half Duplex RS485 (2-wire)
To ensure voltage balance between the devices, the common terminal (GND – pin
5) must be connected to the corresponding terminals of each device. If the
common conductor is not installed between all devices, they should be grounded
according to the manufacturer’s recommendations. In this case you should
ground the common terminal (GND – pin 5) of the converter.
The need to use termination resistors depends on the total length of the
communication bus and the communication speed configured.
USB-i485 Converter has internal termination resistors, which can be connected
by including the dotted connections shown in the figure above.
For more information on termination resistors, see the document RS485 and
RS422 Basic Concepts, available on our website
www.novusautomation.com.
RS422
The connection already described for RS485 Full Duplex (4-wire) meets the RS422 interface specifications. Use this connection method to apply the USB-i485 Converter in an RS422 communication system.
LED OPERATION
USB-i485 Converter has two LEDs:
- TX LED: Lights up when transmitting data to the RS485/RS422 bus.
- RX LED: Lights up when receiving data over the RS485/RS422 bus.
If there is a contact problem or the bus wires are reversed during connection, it is possible that one of the LEDs will be constantly on. If this happens, you should check the wire connection.
CONFLICTS WITH OTHER USB DEVICES IN WINDOWS
In some cases, there may be a conflict with other USB device on the computer
(mouse or other Serial/USB devices, for example) when you are installing the
USB driver for USB-i485 Converter. In this case, follow the procedures below
to try to restore normal operation of the affected device:
Go to the Windows Control Panel and access the USB-i485 Converter properties:
Control Panel → System → Hardware → Device Manager → Ports (COM & LPT)
Select the desired “USB Serial Port” device, click with the right mouse button
and select “Properties”. Select “Port Settings” tab and click on the
“Advanced” button. Uncheck the “Serial Enumerator” option:
TECHNICAL SPECIFICATIONS
| Computer Interface | USB V1.1 Plug and Play |
|---|---|
| Operational system virtual serial port driver | Windows®; MAC; Linux. |
Field Interfaces
| RS485 Half Duplex (dual buses) RS485 Full Duplex
RS422
Data Rate| From 300 bps to 250 kbps.
Maximum RS485/RS422 cable length| 1200 m
Maximum number of devices in the RS485 network| Maximum number of
devices in the RS485 network (unit load devices – 12 kW):
· Half Duplex: 2 x 32 devices
· Full Duplex: 32 devices
Power| From the USB post. Consumption: <100 mA.
Isolation| 1500 Vcc (1 minute) from USB interface and the RS485/RS422
interface.
RS485/RS422 bus protection| ±60 Vcc, 15 kV ESD
USB Connection| Mini-B connector. A 1.5 m cable with plugs mini-B and A
is provided with the device.
RS485/422 Connector| Screw terminal type accepting 1.5 mm² (16 AWG)
wires.
Operating Environment| 0 to 50 °C, 10 to 90 % relative humidity, non-
condensing.
Communication protocol| Jumper selected RS485 / RS422.
Flow Control| Automatic flow control for RS485 Half Duplex.
Internal Terminating Resistors| 120 Ohms internal resistors termination
enabled by jumpers.
LEDs| Transmission and reception of data.
ABS Housing| 70 x 60 x 18 mm.
Certifications| CE
CERTIFICATIONS
CE Mark
This is a Class A product. In a domestic environment, this product may cause
radio interference in which case the user may be required to take adequate
measures.
WARRANTY
Warranty conditions are available on our website www.novusautomation.com.