Serial RS-232, RS-422, RS485 Adapters

The Serial RS-232 Signal Difference

RS-232, RS-422, RS-485 Information

We receive many support calls with regard which serial adapter is needed for a particular serial application. RS-232 connections are the physical interfaces in which one data bit of information is transmitted to serial communication devices such as modems, terminals, Ethernet devices and other various types of peripherals. It is the standard in serial communication. While higher speed capabilities have been developed using USB and Firewire, the standard DB-9 Pin serial port has remained in industry.

RS-232 DB-9 pin out diagram.

PIN SIG. Signal Name DTE (PC) DB-9 Pin out chart
1 DCD Data Carrier Detection IN
2 RXD Receipt of Data IN
3 TXD Transmit Data OUT
4 DTR Data Terminal Ready OUT
5 GND Signal Ground
6 DSR Data Set Ready IN
7 RTS Request to Send OUT
8 CTS Clear to Send IN
9 RI Ring Indicator IN

USB to Serial Adapters in general are manufactured in many forms from molded cables, mini adapters, single port, multi-port, industrial metal chassis, and plastic less rugged cases.

Serial Signal Difference

RS-232 Adapters

On the technical side of the differences, RS232 is a single-ended signal with a specification that allows for data transmission from one transmitter to one receiver at a fairly slow data rate of up to 20K bits/second over short distances of up to 50Ft. using a maximum data rate. RS232 signals are represented by voltage levels with respect to a system power / logic ground. The “idle” state has the signal level negative with respect to common (signal ground in chart above), and the “active” state has the signal level positive with respect to common.

RS-422 Adapters

RS-232 doesn’t interpret well when communicating at higher data rates and over longer distances in actual day-to-day usage environments. RS-422 compensates in its wiring compared to RS-232 to create “differential data transmission” or balanced differential signal.

RS-422 incorporates much better performance in most serial applications; using differential signals can help invalidate the effects of ground shifts and induced noise signals. These signals can sometimes appear as common mode voltages on a network; RS-422 recognizes this noise and produces a much clearer and accurate signal. Signal modes such as RS-422 and RS-485 can also be selectable via DIP Switch or Terminal Wire which is directly wired to a Terminal Block from an outside source.

The RS-422 differential data transmission is designed for 100Kbps and for transmitting at distances of up to 4000 Ft. RS422 is also designated for multi-drop “party-line” communication applications where there is only one driver connected to and transmits on, a “bus” of up to 10 receivers. See the RS-422 wiring diagram below:

USB to RS-422 Wire Diagram

Data Signals Supported by RS-422 and RS-485

  • RS-422 data signals: TxD-, TxD+, RxD+, RxD-, GND, RTS-, RTS+, CTS+, CTS-
  • RS-485 4-wire data signals: TxD-, TxD+, RxD+, RxD-
  • RS-485 2-wire data signals: Data-, Data+

RS-485 Adapters

RS-485 signal adapters are basically a go between from the converters to the terminal or PC using RS-485 signal levels, in other words, the format, speed, and protocol of the data during transmission is not governed by RS-485. The similarity between devices from various manufacturers does not assure compliance with the signal levels by itself. The RS-485 signal is a two wire system that is either a straight or twisted pair wiring construction with a maximum of 32 transmitters and receivers can be operated. RS-485 also keeps the 100Kbps over a length of 4000 ft. transmission rate that the RS-422 specification does. See the straight and twisted pair wire diagram below:

RS-485 Wire Diagram

Fortunately as mentioned in the beginning of this post, there are many different types of serial cables, adapters, or converters for completely different types of serial application uses. Because of the transmit and receive functions of all these serial signal types, troubleshooting data transmission if needed is generally done by reading the adapter’s RXD/TXD LED indicators if provided on the device.

Keeping up with USB Hubs

Keeping up with USB Hubs, their technological advantages, and increasing usage…

The USB Hub Challenge?

It can be challenging to keep up with the amount of information and equipment needed for any industry, CG-1600i-RM - 16-Port USB 2.0 Industrial Hub imagehaving the correct USB hub to empower that equipment is paramount to business operation.

We at CoolGear are finding more often than not that the need for peripherals through a Din-Rail or Rack-Mountable hub has increased in high end companies such as HP, Time Warner, and Redbox to keep up with consumer demands and system use.

We develop our industrial USB hubs thinking about the needs of various industries. We’ve started our new blog off with and introduction to our new USB 2.0 industrial hub, have a look at the details below and feel free to ask a question.

The CG-1600i-RM Industrial USB 2.0 16-Port Rack Mountable Hub, it is USB powered by an industrial-grade switching power supply and provides normal operation in wide ambient temperatures from -40°C to 70°C (-40°F to 158°F) operation in a harsh environments with 15Kv ESD protection. The hub is backward compatible with USB 1.1 and provides for full 500mA of power to each of the connected USB devices.

Technical Advantages – USB Hub Information

  • Adds 16 USB 2.0 ports for peripheral use
  • Industrial-grade metal case
  • DIN-Rail compatible mounting options
  • 19” Rack compatible mounting options
  • Over-current detection and protection on all ports
  • Provides 500mA @5VDC to all ports
  • Supports USB 2.0 transfer speeds of 480Mbps and backwards compatible with USB 1.1
  • Plug-And-Play; No software or extra drivers required
  • 15KV ESD protection
  • LED status indicators for hub power and port connections
  • Supports wide operating temperate range: -40 to 70C (-40 to 158F)

Who should be using 16-Port USB 2.0 Hubs?

As mentioned above, high end businesses are trying to keep up high demand processing, we’ve provided a list of industries we have provided for both in an industrial and commercial environment, these industries include but aren’t limited to:

  • Aerospace
  • Airlines or Aircraft
  • Broadcasting
  • Defense
  • Education
  • Electronics
  • Marine
  • Manufacturing
  • Publishing
  • Retail
  • Software Development and more.

CG-1600i-RM Rack Mountable USB 2.0 Hub

The rack mountable hubs are designed to go through a rugged environment and handle large amounts of data with USB devices such as portable storage devices, reaching speeds of up to 480Mbit/s at Hi-Speed per port, rack mounting the hubs allows the user to better organize their cabling system to support the devices connected to it. This particular hub is manufactured with screw lock mechanisms on each USB port including the upstream type “B” at the hub connection. Din Rail mounting is supported for flat surface mounts.

USB Hub Speed Information:

  • USB 1.1 speed from 1.5Mbps to 12Mbps
  • USB 2.0 backward compatible with USB 1.1 reaches speeds of up to 480Mbit/s Hi-Speed (in the example above this time is now cut to approximately 15 to 20 minutes at full bandwidth.)

The CG-1600i-RM operates at both USB 1.1 and USB 2.0 speeds; the above speed information is the standard specification for this version of the technology. The hub’s power input is 110-220V AC and is equipped with LED indicators for both power and USB port status while in use.

Check back often as CoolGear continues to keep up with technology, and keep you informed!

USB Serial ANDROID Tablet Support

CoolGear USB Serial Adapters work on Android Tablets. We tested it on our Google Nexus Tablet built by ASUS and it works Great!

Here is what you need:




NO ROOTING REQUIRED Just Connect the CoolGear USB Serial Adapter USBG-232 to the CG OTG Cable, then plug into your tablet. Both LEDS should blink which shows it has power and can Synchronize. Now download the Termianl Software once complete click Connect on the Slick Dev Labs Terminal Software and it should connect, on our test it showed up as adapter 2003. For Test purposes we connected our DB9 Gender Changer that is Jumpered on Pins 2 and 3 to use as a Loop back test. This terminal Software is Fully configurable by baud Rate, Parity, Data Bits and Stop bits.


You could use this adapter to gain Access into your Router, Arduino Duemilanove any other Terminal Based Device, this is a Dream for IT Department to gain access to your CISCO Router,  you wont have to carry your laptop anymore!


Android is a trademark of Google Inc.