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dnc to ot

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Aluminum
Joined
Sep 15, 2006
Location
albany ny
need to DNC from Edgecam communications to takisawa(1988) fanuc OT control.
can anybody tell me how?settings,parameters,handshake,etc? lathe is rs232 connected.
not familiar with this setup.

thanks
 
scrapbin:

Do you need to do DNC (Direct Numerical Control) or do you simply want to transfer files from the computer to the CNC memory? My guess is the later.

I suspect that if the CNC has a 25 pin D type RS232 connector that you will need to jumper pin 4 to 5, and separately jumper 6, 8, and 20 together. You would then need three wires to run to the computer and the cable shield only connected to pin 1 at the CNC.

SchneiderMachine:

Is there some real need for 2 stop bits? Will errors result with 1 stop bit?
Why not a higher baud rate?
Is this model of Fanuc only functional with even parity?

.
 
gar,
I suspect it really doesn't make any difference as long as the 2 (pc and control) are set the same. I haven't played with changing anything in my control as it was set that way, I think, by default. It may or may not have something to do with the way the old tape readers read the info. You may be able to go higher with the baud, haven't tried it yet but may at a later date. Higher baud may cause problems, sometimes not (9600 is max in my fanuc I believe) but it's really dependent on the quality of your cable and the length. I run my Milltronics at 19200 baud (that's max) and haven't had any problems but the cables are only 50 ft long and I kept them as far away from the fluorescent light ballasts as I could to minimize high frequency interference. My lathe programs tend to be extremely short in comparison to mill programs so it doesn't make any difference to me. I only use the pc to back up programs anyway as the memory in my lathe is very small.
Dave
 
SchneiderMachine:

I believe that modren UARTs based on the 16550 chip are always in the 1 stop bit mode for receive independent of the number of stop bits programmed. This means stop bit programming only relates to the transmission direction. A second stop bit slows your effective data transfer by about 10%.

If you program the computer for 1 stop bit and the CNC for two stop bits and send data to the CNC and massive errors do not occur, then my conjecture is correct. If a few errors result, then some other limitation exists in the CNC.

In ballpark numbers with 9600 baud and 1 stop bit your transfer rate is about is about 960 characters per second. Thus, a 100k file will take about 100 seconds to transfer. Over a minute and a half.

For a given cable capacitance per foot the maximum cable length for most applications will be about inversely proportional to baud rate. Lower capacitance cable increases your useable length for a fixed baud rate.

.
 
been downloading files to machines.need to dnc to fanuc,only 8k memory on lathe.would like to do the whole part without breaking up instructions in CAM and having to download-delete-download-delete.
 
scrapbin:

You do need to DNC (drip feed). I can not help you with how to setup Fanuc. It may not have DNC capability.

You will most certainly have to work with a handshake. Whether hardware would be better than software I do not know. I think I would try software first.

What is going to be very important is at the computer end you must disable the UART FIFO. Fanucs are known to have very small input buffers for serial data. By disabling the computer FIFO (first in first out buffer - a hardware buffer in the UART chip) you reduce the possibility of overflowing the Fanuc receive buffer.

To disable FIFOs go to
ControlPanel\System\Hardware\DeviceManager\Ports\the particular COM port of interest\PortSettings\Advanced and uncheck UseFIFO buffers and click OK.

Only if software handshake causes errors would you want to change to hardware handshake, or if Fanuc won't work with software handshake. Maybe the manual will have some indication.

.
 
need to DNC from Edgecam communications to takisawa(1988) fanuc OT control.
can anybody tell me how?settings,parameters,handshake,etc? lathe is rs232 connected.
not familiar with this setup.

thanks

What version 0T? My 0T-Cs are 9600, 8, e, 1. I have an old 486dx running DOS 6.22 using a tiny program designed for Fanuc controls to download, upload, DNC and edit. programs. PM me and I'll send you the program.

I don't think the Edgecam comm will let you DNC.

You're not using canned cycles?
 
DNC to 0T

You probably can't run in "drip-feed" or "direct" DNC mode on a 0T. The 0M control has an interface bit which is accessible to the ladder logic for DNC mode, but I don't think the 0T has it. A 0M that has a TAPE mode on the mode select switch, or some other way to set this bit in the ladder can drip-feed, but my guess is that you can't.

Before breaking up a long program, try changing your post to:

1) Eliminate space characters
2) Eliminate N-numbers (unless you need them for canned cycles)
3) Eliminate trailing zeros in your numbers (X1.2300 is not necessary, X1.23 will do)

If these steps don't compress your file enough, think about adding some CMOS RAM chips to the control. 8K is not the maximum possible.
 
1 stop bit vs. 2 stop bits

The standard setting for most Fanuc controls is 4800 baud and 2 stop-bits. Which is really not "standard", but the Japanese swear by it. When you use 2 stop bits, there are 11 bits per character (7 data bits + 1 parity bit + 1 start bit + 2 stop-bits). Think of the start & stop bits as the "Pause" between characters.

Each device has a UART chip (Universal Asynchronous Receiver Transmitter), which runs at a clock frequency determined by the quartz crystal clock on that device. Since all quartz crystal clocks are NOT created equal, there will always be a bit of variance between the clock speeds of the two UARTs that are trying to communicate. This is why the UART chip itself has circuitry to automatically synchronize themselves to each other's data stream. The chip can adjust itself to synchronize as much as +/- 5% or so. This is why it's sometimes possible for two devices to communicate OK when one is set to 1 stop-bit and the other is set to 2 stop bits. This is not a good idea, however, because the UART has to re-sync to the data stream on every character. Some errors are almost bound to occur sooner or later. There are also cases where "synchronous" data transmission is used between two devices, but that requires the use of clock signals that are carried between devices with separate wires in the cable. The only use for synchronous interfaces I've seen is for the old Fanuc Remote Buffer board's RS422 port.

The best bet is to set BOTH devices to the same stop-bits setting. It really doesn't matter whether you use 1 stop bit or 2, but gar is correct when he says that 1 stop bit is standard for all baudrates above 110.

The old ASR Teletype machines used 110 baud and 2 stopbits to give a data throughput of 10 characters per second. This is 110 bits per second divided by 11 bits per character. (that's why it's 110 baud and not 100 baud). When you go to 300 baud, the speed is based on 300 bits per second and ONE stop bit (30 cps.) 600 baud is 600 bits/sec and ONE stop-bit, or 60 ch/sec. (etc.) If you run at 9600 baud and 1 stop bit, you get 960 cps. If you set 9600 baud and TWO stop-bits, you get a slightly slower 873 cps, which is 9600 bits/sec divided by 11 instead of 10.

Bottom line is this: If you don't match the baudrate setting between two devices, you get garbage. If you don't match the stop bits settings, you might get good data most of the time, but why take the chance. Always match the stop bits settings for good communications.
 
Thanks to Dan and gar for the info, very good. I am a self taught kinda guy, no one at work had a clue how to do rs232. All I know I learned by myself, just enough to be dangerous. The settings I referred to were what I had in the machine, I made the pc match and it worked. Time to experiment.
Dave
 
Dan is your expert on Fanuc.

But I want to slightly differ on crystal oscillators. These are extremely precise and stable.

From Bliley an old line crystal manufacturer:
[FONT=Arial, sans-serif]The crystal controlled clock oscillator (XO) is a device that achieves its temperature stability from the quartz crystal's inherent temperature stability (see also crystal oscillator). This characteristic is typically specified in tens of parts per million (ppm). The initial accuracy at room temperature (+25 °C) is dictated by the calibration of the crystal for the most part. A typical calibration tolerance for an AT crystal would be ±10 ppm.[/FONT]
[FONT=Arial, sans-serif]A frequency adjustment circuit could be incorporated so that the nominal frequency at room temperature could be adjusted for aging. This frequency adjustment would be achieved by use of a trimmer capacitor and the typical adjustment range would be ±10 ppm to ±20 ppm. With this type of adjustment the frequency at +25 °C could be set to ±1 ppm typically.[/FONT]

Note 10 PPM is 0.01%. (edit) No it is 0.001%, 1/100,000, sorry. (end edit)

Typical UARTs have built in prescaler of 16 and if the maximum baud rate was set at 115.2 kbaud then a crystal at 1.8432 MHz gives precisely this value. Suitable integer divisors of the 115.2 provide all the larger standard baud rates from 150 up that are precise with no error other than the small error of the crystal. 150 is 1/768 of 115.2 k. Sometimes various other divisors are used and these produce deviations from the ideal. For anything in the last 20 to 30 or more years I see no reason for not using a good source frequency. Note: any integer multiple of 1.8432 MHz is a good source. For example 12.9024 MHz could be used, requires a divisor of 7.

A stop bit is essentially the rest state when no data is being sent and is a logic 1. At the RS232 signal level this is inverted and is a negative voltage. Usually about -10 V in older systems and most CNCs. Some newer computers are using a value nearer -5 V, Dell in particular. A logic 0 is roughly the same magnitude as the negative value but is positive.

The transition from the rest state to a loigic 0 is the beginning of the start bit. This initiates the next conversion of a serial word to a parallel word.

To determine if one stop bit will work I would send plain text, program code is good, to the extent of several hundred thousand bytes and if there were no errors, then I would consider it safe.

I send hundreds of millions of characters with 1 stop bit with no errors and at 115.2 kbaud.

I do think that Dan has a potentially valid argument if there were some bad designers out there. But then even 2 stop bits might not be a real solution to error free operation. If by chance a UART when programmed for 2 stop bits required these in the receive mode, then you would immeadiately see errors.

.
 
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