Film-Tech Forum ARCHIVE: How long can a serial cable be for plugging into a data port CP500

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Posted by Frank Dubrois (Member # 3042) on 06-19-2006, 02:13 PM:

Im just curious if there is a problem with using a really long cable to plug into the data port of the CP500 or 650. I was thinking that if I got a longer cable, I wouldnt have to stand right at the sound rack and juggle my laptop. Would a 25ft serial cable or possibly a long USB cable be a BAD idea?

Posted by Scott Norwood (Member # 30) on 06-19-2006, 02:21 PM:

You should be able to go up to 50 feet without any problems (that is the official length limitin the RS232 specification). If you use cat. 5 cable and/or operate at data rates lower than 19200 baud, you can go somewhat farther.

I don't remember about the CP650, but the CP500 doesn't actually require the use of a laptop to do the B-chain. Everything can be done using the front-panel controls. Older Dolby processors (CP50, -55, -65, and -200) require an extender card for the EQ modules.

Posted by Monte L Fullmer (Member # 2797) on 06-19-2006, 10:05 PM:

Using the serial out if a DA-20 adapter is attached to the Dolby CP-55 units..with the WinDRAS program in the laptop..

(On the CP-500,the serial port is good for capturing the EQ settings to a text file using the DOS LOAD-500 program.. in case the settings crash where you can then just uload those text files back into the CP-500 ..using the LOAD-500 protocol ... or even using Windows default Terminal program...)

And the serial connection have to be a cable that has the same pinout wire configuration for each connector...pin 1 to pin 1, pin 2 to pin 2 ..etc..

If your laptop only has USB, then you have to get a USB to serial interface cable....

Null Modem cables are for the DTS readouts..to laptop ..at least the DTS-6AD .. not familiar with the XD-10 units...

--Monte

Posted by Frank Dubrois (Member # 3042) on 06-19-2006, 10:18 PM:

I have a keyspan serial to usb. On the CP500, it wont plug in. I removed the automation cable, but the serial jack on the CP500 and the keyspan adapter both have screw recepticles which prevents them from connecting. I guess I need an extension cable anyway, so that should work ok.

Can I use the keyspan adapter for the DTS readers too?

Posted by Stephen Furley (Member # 1277) on 06-20-2006, 05:45 AM:

Scott is correct, 50 feet is the official limit. It seems to be a very convervative figure however; I've driven serial printers at several times that distance over simple unscreened burglar alarm cable at 19,200. This was in an electrically 'quiet' environment, but you certainly shouldn't have any problems at 25 feet. RS-422 will go considerably further than RS-232.

The maximum distance is probably the main reason why USB hasn't totally replaced traditional serial interfaces. We still use them for things like interactive whiteboards, and the magnetic swipe card readers on the entrance barriers.

Posted by Monte L Fullmer (Member # 2797) on 06-20-2006, 01:10 PM:

quote: Frank Dubrois
Can I use the keyspan adapter for the DTS readers too?

Nope ... need different test equipment for that reader.

-Monte

Posted by Frank Dubrois (Member # 3042) on 06-20-2006, 03:26 PM:

Like what?

Posted by Frank Dubrois (Member # 3042) on 06-20-2006, 09:10 PM:

If need to get an extension cable, I need one where the pins are connected to corresponding numbers right? 1-1, 2-2, 3-3? I saw a small adapter, but it was listed as a null-modem adapter. The pin configuration was all goofy.

Also, I saw a post a while ago about updating the CP500 with a laptop running Windows XP. Does anyone know if that has been changed with firmware upgrades or windows service pack upgrades? If not, what can I do to upgrade our processors without making a Win98 dual boot? I have Windows 2000 as well, would that work instead of XP? I dont wanna ruin our CP500.

Posted by Monte L Fullmer (Member # 2797) on 06-21-2006, 01:04 AM:

Every windows that I know of have the simple program called "Hyperterminal" - be in your accessories/communications tab in the "program" listing.

Read your CP-500 manual on how to use "Hyperterminal" - works like a charm and you won't hurt your CP-500.

After you know how to use this program, you'd be thankful that you did - in saving all of your EQ settings that you did in each of those units on your laptop..FOR 500's love to lose their settings in which the unit will then revert back to factory default.

-thx Monte

Posted by Frank Dubrois (Member # 3042) on 06-21-2006, 02:17 AM:

Ok...but I heard that there is something with Windows XP that sends current through the cable and might fry the CP500. I wish I had the link to the post...but it is in the forum here somewhere.

Posted by Stephen Furley (Member # 1277) on 06-21-2006, 02:56 AM:

The RS-232 serial ports on PCs carry only data, there is no power supply line there, so even if you incorrectly wired the cable, you would be unlikely to do any damage. RS-232 does not use standard TTL Voltage levels, a positive Voltage is used to represent a logic 0 (space), and a negative Voltage is used to represent a logic 1 (mark). Both positive and negative Voltages used are in the range of 3-25V; the meaning of a transition Voltage, between -3V and 3V is undefined. All RS-232 devices must accept Voltages within this range; though the line drivers normally source lower Voltages, +/- 12V, which allows a considerable loss in transmission to still deliver an acceptable signal to the receiver.

This page gives details of the RS-232 interface.

There have been a few devices which have used serial interfaces which are similar to RS-232, but using standard TTL signal levels, but I've only ever seen a couple of these, and they were designed so as not to be damaged if standard RS-232 signals were connected.

There should be no way that Windows, or any other software, can cause a PC to output a Voltage on a RS-232 serial port that can damage another RS-232 port connected to it. This is simply not within the control of the software, it is a function of the line drivers. If the hardware was badly designed, or faulty, then this could happen, many years ago I saw a computer where loading a certain value into a certain memory location would put a direct short across one of the power supply lines, but this would apply whatever operating system the machine was running.

Posted by Frank Dubrois (Member # 3042) on 06-21-2006, 01:23 PM:

Well, here is what I read right here in the forums:

John Bartow:

"PLEASE NOTE!
To anyone with XP. Load500 does work, but only to download and save settings. If you try to upgrade the software you WILL fry the ROM chips. (this is not a maybe, it WILL fry them) However, with VPC2004 and win98 or DOS, no problems."

Trevor Bailey:

""Fry" might not be an acurate description. As Ken from Dolby explained it: After erasing the EEPROMs, the program will hang when trying to write the new code to the EEPROMs...so you will have two blank chips. The CP-500 will power on but you will have a blank screen and all of the softkey LEDs will be on giving you...one brain-dead CP-500!!
[thumbsup] "

Both said that on here Jan/04. Thats why I'm wondering if XP has come out with an update or Dolby has different software to use in order to update the CP500. I'd hate to think I need a different operating system just to update the CP500.

Posted by Steve Guttag (Member # 268) on 06-21-2006, 02:43 PM:

Dolby has come out with an update...Load500 version 2 which can be found here on Film-Tech in the manuals section under "software".

Posted by Frank Dubrois (Member # 3042) on 06-21-2006, 02:45 PM:

And that will cure the Windows XP problem? I just wanted to be sure before I ruin equipment.

Posted by Steve Guttag (Member # 268) on 06-21-2006, 05:10 PM:

That IS the purpose of version 2...to work with XP (and earlier). I've used it myself with an XP puter on several CP500s and all is well.

Posted by Greg Mueller (Member # 17) on 06-22-2006, 09:03 AM:

RS232c is a great communication medium, why they replaced it with USB I'll never know.
Anyway you can run hundreds of feet with RS232, I've done it and do it all the time. What's more I do it in a "noisey" rf environment (cnc machine tools). Personally I have run 250 feet of 232 without problem.

Posted by Steve Guttag (Member # 268) on 06-22-2006, 09:41 AM:

It really depends on the wire, the speed and just how well everyone is obeying the RS232 spec.

Posted by Frank Dubrois (Member # 3042) on 06-22-2006, 01:31 PM:

I'd like about 25 feet of movement space. Do you think its ok to just get an extension for the USB end? Everyone in town seems to only have 6' serial cables. I can easily find a 10' USB extension. I need it now...otherwise I'd order it on ebay.

Posted by Greg Mueller (Member # 17) on 06-23-2006, 08:55 AM:

I think max USB is 15-16', but I bet you could push it.
When you get the time, check cyberguys.com for cables and other neat gizmos.