What is RS-232?

• First intro­duced in 1960, RS-232 used to be the main stan­dard for ser­i­al ports for com­put­ers and is still wide­ly in indus­tri­al appli­ca­tions today.
• It defines the sig­nalling between a DTE (data ter­mi­nal equip­ment), such as a pro­tec­tion relay, and a DCE (data cir­cuit-ter­mi­nat­ing equip­ment or data com­mu­ni­ca­tion equip­ment), such as an RTU.

• RS-232 is only used for point-to-point com­mu­ni­ca­tions, i.e. it only sup­ports com­mu­ni­ca­tions between two devices as for exam­ple a mas­ter and a slave device in a Mod­bus network.

• The max­i­mum speed of RS-232 is around 115Kbps with a max­i­mum dis­tance between net­work devices of about 30m.

• So it has some draw­backs in com­par­i­son to lat­er devel­oped inter­faces such as RS-422, RS-485 and Eth­er­net, such as a large volt­age swing, large con­nec­tors, no mul­ti­point capa­bil­i­ty, lim­it­ed mul­tidrop capa­bil­i­ty and the lim­i­ta­tions in terms of trans­mis­sion speed and range.

Ethernet vs RS-232 vs RS-422 vs RS-485

It is impor­tant not to con­fuse com­mu­ni­ca­tion pro­to­cols with stan­dards for elec­tri­cal char­ac­ter­is­tics of phys­i­cal com­mu­ni­ca­tion media. Dif­fer­ent com­mu­ni­ca­tion media are used depend­ing on project needs. The stan­dards’ main dif­fer­ences are the com­mu­ni­ca­tion speeds, the max­i­mum num­ber of con­nect­ed devices and the phys­i­cal dis­tance between con­nect­ed nodes.

RS-232
The RS-232 (Rec­om­mend­ed Stan­dard 232) or also known EIA-232 (Elec­tron­ic Indus­tries Alliance-232) stan­dard is used only in point-to-point com­mu­ni­ca­tions, i.e. it only sup­ports com­mu­ni­ca­tions between two devices, which in the case of the Mod­bus pro­to­col would be a mas­ter and a slave device. The max­i­mum speed of RS-232 is around 115Kbp/s with a max­i­mum dis­tance between net­work devices of about 30m.

RS-422, or also TIA/EIA-422, was intend­ed to replace the old­er RS-232C stan­dard with a stan­dard that used dif­fer­en­tial sig­nalling to pro­vide high­er speeds, longer cable lengths and less noise. At short dis­tances, data trans­mis­sion rates can reach up to 10 Mbit/s. At low­er rates, data can be send through cables with a length of up to 1,500 meters.

RS-485
The RS-485 (Rec­om­men­dad Stan­dard-485) or EIA-485 (Elec­tron­ic Indus­tries Alliance-485) stan­dard is one of the most wide­ly used stan­dards for ser­i­al com­mu­ni­ca­tion in indus­tri­al appli­ca­tions. The main dif­fer­ence with RS-232 is that it allows more than two devices on the net­work, enabling to have sev­er­al slaves. It achieves rates of up to 12Mbps and in rar­er cas­es up to 50Mbps, while the max­i­mum dis­tance with­in the net­work is 1200m, and the max­i­mum num­ber of devices on the net­work is 32.

Eth­er­net
Depend­ing on the vari­a­tion used, tran­simis­sion speeds with Eth­er­net range from 100Mbps and up to 10Gbps, while max­i­mum dis­tance can vary from 100m to 200m depend­ing on project con­di­tions and the type of cable used. In some cas­es, it is pos­si­ble to use fiber optic net­works, which enable longer dis­tances and high­er com­mu­ni­ca­tion rates, as well as wire­less communication.

Automation with IEC 61850 

The IEC 61850 stan­dard is enabling new opor­tu­ni­ties for ven­dor inter­op­er­abil­i­ty and advanced sub­sta­tion automa­tion. Find out how you can take advan­tage of IEC 61850 with easy-to-use and adapt­able solu­tions for a sim­ple migra­tion or retrofit.

HV Substation Automation

Pow­er­ful sub­sta­tion automa­tion sys­tems often han­dle numer­ous com­mu­ni­ca­tion pro­to­cols and media with­in one net­work, which can result in expen­sive and com­plex projects.  Avoid these prob­lems with inter­op­er­a­ble tech­nol­o­gy and smart con­fig­u­ra­tion tools.

MV Distribution Grid Automation

It is often dif­fi­cult to find the exact solu­tion you need in a MV appli­ca­tion, lead­ing to high­er costs than nec­es­sary. With our scal­able and adapt­able solu­tions you will be able to only pay for what you real­ly need, with­out com­prim­is­ing on qual­i­ty or security.

Photovoltaic Power Station

Using an open and scal­able SCADA sys­tem to mon­i­tor and con­trol a PV plant comes with many ben­e­fits on sev­er­al lev­els. Find out how advanced com­mu­ni­ca­tion tech­nol­o­gy affects PV oper­a­tion, main­te­nance, sys­tem design, invest­ment secu­ri­ty, profits…

Protocol Conversion

As com­mu­ni­ca­tion net­works grow in com­plex­i­ty, “plug and play” promis­es become hard­er to keep. Inter­op­er­a­ble pro­to­col con­vert­ers and soft­ware solu­tions with state-of-the-art capa­bil­i­ties and funci­tonal­i­ties can be the bridge to all the func­tions and flex­i­bil­i­ty your net­work needs.

Generation Dispatch Control Center

With a gen­er­a­tion dis­patch enter you can auto­mat­i­cal­ly con­trol the gen­er­a­tion of all pow­er plants and make direct bids for ancil­lary ser­vices on one plat­form. Check out the most effi­cient com­mu­ni­ca­tion path between gen­er­a­tion sites, grid oper­a­tors and the pow­er market.

Smart Metering

A sin­gle device that col­lects, process­es, trans­fers smart meter data and load curves from sev­er­al meters in dif­fer­ent pro­to­cols via ser­i­al or Eth­er­net, whilst pro­vid­ing advanced automa­tion func­tions? Adapt­able designs and a full com­mu­ni­ca­tion pro­to­col suite make it possible. 

Switchgear & Transformers

Some­times you have pre­ferred gear for a project or it has already been installed, but it is lack­ing the com­mu­ni­ca­tion capa­bil­i­ties to pro­vide the automa­tion func­tions you are look­ing for. With our soft­ware core iGComms any device can be as smart as you want it to be.