Problem- Line Noise (COM via Predator/RocketPort)

[SeanO]

Hi All,

We are seeing some junk come through some of our machine's DNC COM in Predator (see screenshot).

Our wiring is shielded CAT5E from the server to the RocketPort. There are DB9->RJ45 adapters out the the RocketPort to shielded CAT5E to the machine controller. At the controller, we're terminating with a grounded female RJ45 and using a shielded patch cable to an RJ45->DB25 to the COM port. This particular machine control is a Fanuc 15-M.

90% of the controls are connected this way, only a handful are seeing this 'noise'. I doesn't seem to directly affect that machine, but we do occassionly have port get 'stuck' and need to be reset at the Predator server (version 4.1.0.40).

Any ideas on the cause or way to track down the 'noise'?

Thanks!

[CNCTECHNICIAN1]

Use Predator Grizzly cable. It is good stuff it is double shielded. I have gone in to many shops and fixed noise issues with My Grizzly cable I have.

[inventcom]

Sean,
we had similar problems with older installations that had quit long serial cables. The problem comes from serial communication in general (just low electrical differences form your characters !!) The best solution is to install single TCP/IP RS232 converters directly at the serial interface of the control. These converters do just cost around USD 290 !! After that you may set speed x10 without any noise problems. Datasheet is here (i'm quite shure that there are similar converters from your supplier):
http://ftp.dnc.at/cncnet/_pdf/CNCNETONESPIAEN.pdf

[gm3211]

The RocketPort hardware is designed for RS232 communication cabling to the CNC. By using Cat5 (ethernet cable) you have use wrong type of cabling for the application.

Because most CNCs only require 3 wires to communicate, RD, TD and SG, you sometimes get away with it working for short distances. Most of the time you will not have to deal with the real concern until a scrap part or data lost to the machine, but I can almost bet that if you ran Belden 9933 RS232 cable to the machine on 1 run, it would be resolved.
Also, use the Command timeout in Predator to eliminate the "stuck" communications. Most of the time the file sent to the control has random characters or spaces after the M30 and precent sign and anything after this % is going to be sent to the control my Predator. Yet the machine has closed the port. By using the Command Timeout or even Clean Code, the issue is resolved by the software but does not fix your files.

[SeanO]

Thanks for the feedback. gm3211: we aren't actually having problems with the noise in the program transfers, it just when the machine is idle. I'll try to convice them to run the 9933 cable to that particular machine as a test.

[gm3211]

Very common that noise will be picked up without communication to the machine. You can put an optical isolator on it but the cost for these would be more than running the Belden cable.

Here is a link to pre-made RS232 cable:
http://www.shopfloorautomations.com/cabling.php

[CNCTECHNICIAN1]

Are you drip feeding?? Because if you are getting noise in while idle then something is not closing your port. Be it predator or machine but it all depends on how you are set up. If you are using hardware handshake or software.

[cadcam]

you guys want the best info from Predator stuff follow GM3211 or even just communications I have worked with him for almost 10 years. him and his partner have helped with hundreds of my customers.