Problem- DNC missing characters!

[Place2809]

Can anyone help me with a drip feed problem? WHen I drip feed using Hyperterm or using DNC Precision, there is the odd character missing from the files. This hurts alot when it goes "Z.2643" instead of "Z3.263". I have not noticed it happen while downloading a program, only seen it drip feeding. My settings are 4800,7, even,2 with lots of delay. I have shortened my cable from 15 feet to 3 feet. tried 2400 baud etc, without a noticable change in the frequency of errors. Could there be a seting I do not have right? The machine is an Meldas M0 control on a leadwell mcv-0.

I'm a bundle of nerves and will be standing with my shaky hand over the E-stop waiting for some help! lol.

[A1CNC]

I have 2 leadwell MCV-O's with the MO control.
I made a procedure on how to drip feed them at 9600. I can email it to you if you send me your e-mail adress. It is too big to attach here.

Regards,
Eric

[inventcom]

Place2809,
if you get absolutely(!) the same prob with 2 programs it's most likely a serial interface setting problem, not application - windows! You can try to disable the FIFO Buffer in windows device manager - COM-LPT - select the COM Port - Advanced - uncheck FIFO Buffer.

You may also try with the monitor function of CNCnet DNC. In CNCnet DNC you can also filter specific caracters or use the binary switch in characters to transmit the file as is. http://cncnetdnc.wieland.us/

But from my experience this is some PC pressing characters to the machine and machine not receiving fast enough (it's drip feed)

Martin

[Place2809]

OK, Now I am really tearing my hair out!!!

I ended up being able to drip feed at 9600 and lose one or two characters running three files that are 250kB. Still not prefect. I tried to change to hardware control, couldn;t get it to work. Now I tried to jumper the cable back and now I get a parity H error every time. I have messed the cable up pretty good maybe. Checked my parameters and they were changed from what was put in..... what the @#$%? Cleared everything, put them back in from scratch, (manually, download not working!) and I still have the error. Making a new cable in the morning. Could there be something else screwy?
I have 1,2,3 and 7 thru, 4,5 and 6,8,20 jumpered. Sheild is grounded on the CNC side. Tried a few combo's earlier but now I think I am just getting confused..... need sleep.

[Place2809]

Eric,
Thanks for the info. Tried it. Still had the missing characters.

Martin,
Thank you for the ideas, unchecked the fifi, still didn't help. I also have the buffer down to 1 byte, Could download to memory at 19200 no prob. Drip fed everywhere from 1200 to 19200, handshake delay of 1000ms, chartacter delay of 50, line at 50ms. Frequency was the same even with delays as small as 3ms. Until I lengthened the line delay to 200ms. Character could be 3ms and handshake at 300ms. Then I could get through the program maybe two out of three times.

Maybe I should start from scratch on the setup of this.

Greg

[HuFlungDung]

With a 3 foot long cable, I would not expect any issues due to cabling (once you get it wired correctly )

Have you tried a different PC or a different com port on your PC? Not that it is terribly suspect, but it is maybe one of the easier 'try it and test it' options. I suppose getting a new serial port for the control would be a large PITA, but maybe it has an unused port somewhere in there, that you could switch to for testing. Perhaps it might be using different hardware.

Perhaps another option, if the control has the option, is to run DNC without decimals, that is, run in units of machine resolution. Why would this be any better? I have no idea, but it would be different. Maybe decoding the decimal character causes an issue sometimes.

[gm3211]

Are you using a standard built in serial port on the PC?

USB, added serial card? What?

Also, why not hardware handshake? The parameters support it and the most reliable.

[Place2809]

I am using the standard com port. Not using the USB.

I tried to hardware handshaking but never got it to work.
I made up a new cable for software handshake, shield grounded cnc side. 4800 Baud, 7 Even 2, 5ms character, 150ms line, 1000ms handshake delays using DNC Precision, windows 98, (was using windows 95 but the com port in that computer died giving me the bald spots where I pulled my hair out! lol) Turned FIFO off in the advanced port settings.
I got a couple errors today after a few days of good running but they clearly coincided with the starting of other machines nearby (Well, i hope! lol) So I am tying a large guage ground from the computer chassis to the NC and cutting the ground off the computer plug. Not sure if this will work but I think it should help. Oh yeah, the cable it only 4 feet long so the computer is right there at the NC. If this doesn't work I'll have to put a scope on it and start hunting for the noise.
I do think most of the errors I was getting was from the memory not clearing fast enough for the handshake. I still want it to go faster, but for now I am happy just not crashing every couple hours. Thanks to everyone who posted their thoughts and ideas, they do help.

Greg

[dcoupar]

This sounds suspiciously like a bad ground.

You say you're using the standard COM port... DB9 or DB25? If it's a DB9, pin 7 (Signal Ground) on the CNC (DB25) side goes to pin 5 on the PC side.

Also, have you checked the resistance from Pin 1 (Chassis Ground) on the machine connector to machine ground? Is the machine grounded to a ground rod or back to the panel? Do you have welders, plasma cutters, etc. that cycle on and off when you're drip feeding?