Can the PLC programming cable Extended to 1 km??


Thread Starter


In a case, I need to communication a PLC with PC,but the distance is up to 1000M, I want know if there is a solution.

I have siemens S7-300 plc and siemens s7-200 plc. The PC is in a office, but the PLC is in factory. The PC must communication with the PLC, in order to get the online data.

The distance is too long. I want know if there is a solution?

I just search on google,and find sub product:

It write that it can get max 1000m distance,i want know if anybody have used the product? If the solution is work fine?

Fred Loveless

The easiest way is to have Ethernet Cards and then just use the programming software. If that is not an Option You can use serial to ethernet converters set to talk with each other . Go Serial to a converter that is connected to to a converter onthe shop floor which then connects via the programming cable to the PLC.

For the S7-300 Hilscher makes an Adapter(NL 50-MPI) that will allow you to program the PLC and communicate through it with communications servers that support it.

Fred Loveless
Senior Application Engineer
Kepware Technologies
Easy Solution:

Patton Ethernet extenders can extend the distance of Ethernet segments up to 5 miles over a single twisted pair.

We did this for our CEMS and it's a great easy solution if fiber proves to be too expensive and you got cat-5 on hand.

Good Luck.


Bob Peterson

there are plenty of solutions. if you plant has ethernet, drop a line to the plcs and you should be able to get to them from your office with some firewall and routing help from your friendly IT guy.

there are fiber optic products that can extend profibus that far.

just depends on what you can afford and need.

William Sturm

Call the folks at B&B Electronics, they sell all kinds of serial adapters.  You need something like a short haul modem.  I'm sure that they can help.


Patrick Lansdorf

Hi there,

If you have an ethernet connection close to the PLC, you could use a serial server. HMS has one that works with the MPI/RS232 converter.
So you would select a virtual com port in S7, a software will redirect that com port to an IP-address (the serial server) with is connected to the PLC, via the MPI/RS232 converter. making it possible for you to go online with the PLC from your office.

For more information about the serial server, please go to: Serial Server

or send me an email, [email protected]

why don't you try fiber optic?
what u need then is a fiber optic converter to convert FO to ethernet.
so, you can collect your data's in to your PLC.
MPI works by default with a transmission speed of 187.5 kb/s ... this allows a cable length of 1000m if the cable meet the MPI specification. If the quality of the available cable is bad please check if you can setup a speed of 19.2kb/s. Some PLCs are supporting that transmission
speed ...

Best Regards
Armin Steinhoff

Gabriele Corrieri

... my point of view is that, other comms way over than un-affordable (for control systems) radiowave, and affordable, fast, secure optical fiber there isn't one.

I'm working from 15 year in machine for copper/steel/fiber industry and have not see any comms cable long more than 0,5Km in a single cut; reasons? I want to see everyone here to put underground 1Km of cable single cut ... who assure that during installation this cable is right manipulated?

Other doubt: copper long cable have two electrical problems: the resistance of conductors and different ground voltage between start and end of cable: this could be very dangerous (in a similar situation about 10 years ago I've destroyed -over only 20 meters of wire - a programming adapter and I've put under risk of destruction my serial port and a comm port of plc. For someone that debate that over RS485 this problem isn't present ... I'm answer that adapter convert from RS232 to RS485 ...

A rapid conclusion: for my point of view the only technique to remote programming devices is fiber, and today everything could be converted on fiber.

I solved the long distance ethernet problem by buying a pair of Netgear 'HomePlugs' for about $150 at Best Buy. These things are designed to plug into any 120VAC outlet and have 4 ethernet ports/connectors each.

They are intended for extending your ethernet network in a home by using the existing 120VAC power wiring. But I powered up a twisted pair in the cat5 wire with 120VAC (using appropriate fusing) and I'm getting streaming video at 85 MBS at over 2 KM distance. Have not tested the limits of this scheme yet.

for more details.

Happy Hydro

Gabriele Corrieri

I disagree with this: by your definition (and netgear ...) these are 'home_something' I underline 'home' and not industrial powerline. For simple variable reading or checking I think could be ok, but for programming, forcing variables and so on I disagree: something could be dangerous and cause some damage some meters of wire and emergency stop under hand, I don't think what do or could do a distance of 1km from your laptop and a control room.

My two cents,
Let me get this right, so you powered up a pair in the Cat5 cable with 120VAC? Oh but you fused it appropriately. That should make the inspector happy. With the downturn in the economy I am glad I picked up on this - it will make wiring my next house a lot cheaper!