NI-3100 RS-232 issue

nikhil

Hi,

i am trying to control some devices via RS-232.I am facing an issue. When i am trying to control the devices for some time they are accepting commands but after some time they are not responding with the same commands. But when i am controlling via DataViewer all devices are responding correctly. I checked the cables by shorting Rx and Tx also.
Controllers were installed 3-4 years back and it was working before with the same devices.

Any suggestions plz...

ericmedley

This is pretty vague. Can you be more specific? what device(s)? What commands are supposed to work, work for a while, but then quit working?

RichardHamilton

Are you sure it's only 3-4 years old?

The serial capacitors do die after several years, you may need to arrange a service on the controller.

Normally it's usually about 5 plus years.

John Nagy

Note that upon a cold start, bad capacitors in charge of the RS232 carrier voltage often work again... for a while, usually less than an hour, but long enough to confuse the hell out of the techs.
Add to that the fact that some devices fail at different voltage drops, so some serial will work when others fail, and that 422/485 just keeps working (it does not use the voltage the 232 requires and the caps fail to provide), and you have an elusive problem that is, in the end, CAPACITORS, and you need to send it back to AMX.

TO repost an actual test (which others have said works, but I have not had the opportunity or need to try):

"If you measure the voltage between ground (pin 7) and RX (pin 2) it should read somewhere between -3V to -12V when idling. (AFTER the unit has been powered for at least an hour)
I know one of the pins (RX or TX) should idle at the negative voltage; I?m pretty sure it?s RX.
If you're not getting that then I think it's a sign that the port is dead.

The rs232 spec requires from -5 to -15 vdc. That voltage should appear between the transmit pin (#3 on an AMX DB9) and ground (pin 5). AMX ports that I have measured seem to come out quite well: -9.5 vdc or so. Be careful to not polarity, with a bad port/capacitor, it can be POSITIVE voltage which is wrong."

nikhil

Thanks All,
Eric, Am controlling clipsal CBus, GrandBeing Matrix Switcher and our own Autopatch Switcher via RS232. Everything worked for some time(we cant specify the time), then it stopped again even AMX Autopatch Switcher. From DataViewer, these all devices are working. So we are sure with the commands.From last 2 days nothing was working, but today i checked it started to work again.

John, We measured voltage between transmit pin(#3) and ground(#5). Its coming as positive voltage about +10V. I checked voltage between ground(pin7) and Rx(pin 2). It is somewhat betweeen -10V.

ericmedley

I wonder if you might have the "Capacitor Problem" going on. IT's a physical defect in one of the capacitors on the Rs232 board that manifests itself in rs232 communications. You will see the TX and RX lights working but in actuality the voltages on the pins are not high enough to work. This doesn't explain the issue you mention of commands that once worked not working after a while.

Can you post the strings being sent when they are working vs. when they are not? (Do a Notfications on the serial port(s))

nikhil

Line 1 (16:41:56):: String To [5001:3:21]-[DL0O1T]
Line 2 (16:41:57):: String To [5001:3:21]-[DL0O1T]
Line 3 (16:41:57):: String To [5001:3:21]-[DL0O1T]
Line 4 (16:41:57):: String To [5001:3:21]-[DL0O1T]
Line 5 (16:41:57):: String To [5001:3:21]-[DL0O1T]
Line 6 (16:41:58):: String To [5001:3:21]-[DL0O1T]
Line 7 (16:41:58):: String To [5001:3:21]-[DL0O1T]
Line 8 (16:41:58):: String To [5001:3:21]-[DL0O1T]
Line 9 (16:41:58):: String To [5001:3:21]-[DL0O1T]


These are the strings am trying to send to autopatch. These are the notification when no reply from autopatch. When its working, its just simply replying as

Line 1 (16:41:56):: String To [5001:3:21]-[DL0O1T]
Line 2 (16:41:57):: String From [5001:3:21]-[DL0O1]
Line 3 (16:41:57):: String From [5001:3:21]-[T]

nikhil

Line 1 (16:46:55):: String To [5001:3:21]-[DL0O1T]
Line 2 (16:46:55):: String From [5001:3:21]-[DL0O1T]
Line 3 (16:46:56):: String To [5001:3:21]-[DL0O1T]
Line 4 (16:46:56):: String From [5001:3:21]-[DL0O1T]
Line 5 (16:46:56):: String To [5001:3:21]-[DL0O1T]
Line 6 (16:46:56):: String From [5001:3:21]-[DL0O1T]
Line 7 (16:46:57):: String To [5001:3:21]-[DL0O1T]
Line 8 (16:46:57):: String From [5001:3:21]-[DL0O1T]
Line 9 (16:46:58):: String To [5001:3:21]-[DL0O1T]
Line 10 (16:46:58):: String From [5001:3:21]-[DL0O1T]

when am shorted 2&3 pins so I am getting the same command as reply. But some times am not getting that reply also.

I dont know it is the capacitor problem or not. Is there anyway to check capacitor problem?

Draugar

Hi nikhil,
It sounds to me as well that you have a dried out capacitor. The result is that the NI-controller is able to receive commands, but is unable to send any. Test this with a warm controller (been on for some time) and connect the chosen port to your computer to read via HT, docklight or similar programs. See if you can send from controller to PC, and vice versa. Maybe have some distance on the cable you are using as well in case the voltage is high enough to send with 50 cm but not 3 meters.
Hope this helps.

nikhil

Am using dataviewer as PC Interface.When I am sending commands from dataviewer, in netlinx studio notification i can receive it but when i am sending commands from controller i am not able to receive commands in dataviewer now.

ericmedley

nikhil wrote: »

Am using dataviewer as PC Interface.When I am sending commands from dataviewer, in netlinx studio notification i can receive it but when i am sending commands from controller i am not able to receive commands in dataviewer now.

yep - you have the capacitor issue. You can replace it yourself if you are good with a soldering iron. Otherwise, you can send it in to AMX and they'll replace it for the bench fee. ($400 i think)

nikhil

If its a capacitor issue, will its RS485 port work? So if i given command like "'SET BAUD 9600,N,8,1 485 ENABLE'" and after that if i short 2&3 pins. then will i get reply for what I am sending?

ericmedley

nikhil wrote: »

If its a capacitor issue, will its RS485 port work? So if i given command like "'SET BAUD 9600,N,8,1 485 ENABLE'" and after that if i short 2&3 pins. then will i get reply for what I am sending?

If I understand your question - the capacitor issue has to do with a significant voltage drop on the circuit used to send the signal to the device. Don't quote me on this - but the standard is something like 10~12 Volts positive eqals a "1" and a negative voltage equals a "0" the leaky cap no longer passes voltage so the circuit is power starved. It might work for a few bits but the cap quickly loses charge and cannot complete a message string.

If your messages from code are the same in each case there is no reason the device should ignore them. It points to a physical problem. I don't know if the 485 pins use a different section of the board. It's not out of the realm of possibility. But, the capacitor issue is a known problem that exists with practically all NI-X100. Almost everyone on this forum has had to deal with it. The key clues you've mentioned so far are 1) Used to work fine but now doesn't and 2) more than one serial port is effected with same problem.

There is a post buried somewhere on this forum with pictures showing how to replace the cap. Its a cheap and simple way to fix the problem. (here again - if you're handy with a soldering iron.)

John Nagy

ericmedley wrote: »

yep - you have the capacitor issue. You can replace it yourself if you are good with a soldering iron. Otherwise, you can send it in to AMX and they'll replace it for the bench fee. ($400 i think)

AMX has repaired about a dozen for us at a flat $150 each if there is nothing else wrong. That isn't a special price for us.... it's what they've been charging.

If a unit is in for other service, they are automatically replacing the caps at no additional cost.

John Nagy

ericmedley wrote: »

If I understand your question - the capacitor issue has to do with a significant voltage drop on the circuit used to send the signal to the device. Don't quote me on this - but the standard is something like 10~12 Volts positive eqals a "1" and a negative voltage equals a "0" the leaky cap no longer passes voltage so the circuit is power starved. It might work for a few bits but the cap quickly loses charge and cannot complete a message string.

If your messages from code are the same in each case there is no reason the device should ignore them. It points to a physical problem. I don't know if the 485 pins use a different section of the board. It's not out of the realm of possibility. But, the capacitor issue is a known problem that exists with practically all NI-X100. Almost everyone on this forum has had to deal with it. The key clues you've mentioned so far are 1) Used to work fine but now doesn't and 2) more than one serial port is effected with same problem.

There is a post buried somewhere on this forum with pictures showing how to replace the cap. Its a cheap and simple way to fix the problem. (here again - if you're handy with a soldering iron.)

The voltage in question is not a logic voltage. It is a steady carrier voltage, part of the RS232 handshake protocol. The caps regulate that carrier voltage at a nominal 12 volts. When the voltage is or missing, the devices presume the line is dead and do not communicate.

422/485 do not use a carrier voltage, so they don't care that the voltage has gone away.

The caps are easy to replace yourself in a 2000/3000/4000, but in the 21/31/41 series, the surface-mount parts are very challenging to fix without damaging the board in the process.

vining

John Nagy wrote: »

422/485 do not use a carrier voltage, so they don't care that the voltage has gone away.
The caps are easy to replace yourself in a 2000/3000/4000, but in the 21/31/41 series, the surface-mount parts are very challenging to fix without damaging the board in the process.

Yep, hacked up a few boards on 3100's while the 1st 3000 was easy. The last 3101 I tried is still on the bench. I keep ripping up the foil runs trying to remove the bad cap and I'm too stupid to remember what I did wrong the last time.

ericmedley

John Nagy wrote: »

AMX has repaired about a dozen for us at a flat $150 each if there is nothing else wrong. That isn't a special price for us.... it's what they've been charging.

If a unit is in for other service, they are automatically replacing the caps at no additional cost.

I've replaced quite a few myself too. I happen to be pretty handy with a soldering iron. I'm old enough to have existed when we pretty much soldered everything. I can tell you it is a fairly easy job IF you have the right tools. I watched a technician toatly roach the board on a 3100 when he tried using a big soldering gun.

It's best to use a very fine tip on a good 800-ish watt soldering iron. The points are obviously machine soldered and the solder flow is pretty good - so the pin well is filled quite well. You will want a good solder sucker to get the old solder out cleanly. AND don't hang out on the board too long with the soldering iron.

nikhil

Thanks eric and everyone. That was a capacitor issue and I replaced.

John Nagy

OK, I got tired of saying I had not personally tried the voltage test, so I did it on a LOT of known good and bad units over the weekend.

Here's what I found.

First, here's the test:
LOOKING INTO THE DB9 JACK ON THE BACK OF THE NETLINX.... #5 is GROUND (same as the shell)
and pin 3 - the MIDDLE one on the long row - is "TXD" per the back of the NetLinx. That's the one to measure for voltage.

x1 x2 x3 x4 x5

x6 x7 x8 x9

Put your voltmeter NEGATIVE probe on the shell of the DB9 (easier than trying to hold it on Pin 5 and exactly the same thing)
Put your POSITIVE probe against pin 3, the middle one in the long row.

The RS232 specification calls for -5 to -15 volts to engage communication. Note polarity, if POSITIVE, it's BAD at any voltage.

My results-
Known bad units showed no voltage or POSITIVE voltages up to 12 volts POSITIVE across these points.
Known working units showed an average of 6.4 volts NEGATIVE across these points.
A brand new MX1200 showed 6.4 volts NEGATIVE here.
A few suspected bad or intermittent units showed 4 to 6 volts NEGATIVE.
A couple (working- you can't kill them) AXCENT3 units showed -12 volts here.

Hope this helps sort the bad from the good from the who-knows-what

TUTech

That Worked!! I almost can't believe it was that simple and that was the problem. I replace capacitor 206 on the Netlinx 3100. I did lift the run on the board, but soldered it back together and put a dab of super glue on it.