DX9100 Communication Problem

[Koluib]

Metasys Network:In one of the building we have 8 DX9100 and 10 VAVs.3 of the DX9100 are not communicating.These are working fine as a stand alone.
When checked with Converter for 485 Lan connecter ,communicating Failure.
But when checked with Serial cable RS 232 it is communicating,uploading Downloading everything is working fine.What is possible reason not communicating through 485 Lan.Anybody face this problem and knows the solution,any help will be appriciated.

[NINAX]

I'll have to assume that this site was up and running for a while and this issue has just cropped up.

As long as you are doing the N2 converter connection correctly, it's smelling like N2 comm failure. Seen it before. Not that common at all, but I've seen it.

Scan the bus with M-Tool and see what shows up. Watch for mystery controllers or mystery addresses.

You could always swap one of you comm'ing DXs with one of the non-comm'ing DXs and see if the problem travels with the DX. Change address DIP settings. Pick a pair that are most similar to cut down on the AI-AO jumper switching.

[HVAC-DDC-Guy]

You may just try sending a reset command or cycling the DX. These do not always come back online after a commission or download.

[Koluib]

I swap but the result is same.I do not understand cutdown AI-AO Jumper Switching.

[Koluib]

You may just try sending a reset command or cycling the DX. These do not always come back online after a commission or download.

Is it Reset and Recycling the DX same or these are different.Is it Hardware problem,but how come with three controllers.

[HVAC-DDC-Guy]

What he was saying is that if you swap the DX's, changing the addresses, the configuration and jumpers may not match the terminations unless they are all exactly the same.

If you changed the DX's then you have reset them.

You will need to give some info. Were these all running before? What is the front end? Did something happen around the time that they quit (front end change, commissioning, lightning)?

[NINAX]

I swap but the result is same.I do not understand cutdown AI-AO Jumper Switching.

Same problem where? The same controller or the same location?

[freddy-b]

If you have done all the above and they are mapped correctely and have unique n2 addresses...then.........With three doing the same thing its a physical N2 comm bus problem.

Unplug from n2 trunk one at a time and check N2 bus voltages....at plugs and right on DX pins.
+ to Ref should be in the neighborhood of 2.5 vdc
- to Ref 1.5 vdc
+ to - the difference between the two

[Fix-It]

If the the rest of the controllers are communicating and only 3 are not, Double check your wiring(N2 bus) to each DX's. They're normally daisy chained but take note of the polarity. Follow the N2 wiring from each controller...start from the one that's working/communicating properly.

[Koluib]

[QUOTE=freddy-b;1837636]If you have done all the above and they are mapped correctely and have unique n2 addresses...then.........With three doing the same thing its a physical N2 comm bus problem.

Unplug from n2 trunk one at a time and check N2 bus voltages....at plugs and right on DX pins.
+ to Ref should be in the neighborhood of 2.5 vdc
- to Ref 1.5 vdc
+ to - the difference between the two
N2 connector plug removed from Dx and found following readings
Ref to Pos and Ref to Neg on N2 plug fluctuating near 2.2 volts
Pos to Neg fluctuating point 2 volt
At DX Pins
1:Ref to Pos 2.37 Ref to Neg 1.77 Pos to Neg .6
2:Ref to Pos 3.14 Ref to Neg 1.58 Pos to Neg 1.56
3:Ref to Pos 2.77 Ref to Neg 2.02 Pos to Neg .74
Please keep in mind These are working perfect as stand alone and also
Have perfect communications with serial port with serial cable.
Problem only with N2 Bus and N2 converter communication,it mean Protocol485 is angry.Thank you for your efforts.

[Koluib]

What he was saying is that if you swap the DX's, changing the addresses, the configuration and jumpers may not match the terminations unless they are all exactly the same.

If you changed the DX's then you have reset them.

You will need to give some info. Were these all running before? What is the front end? Did something happen around the time that they quit (front end change, commissioning, lightning)?

DX were Swap in different locations with new jumper settings and new addresses,but the same controllers are problamatic at every location.Once NCM power supply was blown some times before.But 75% controllers are communicating normal.

[HVAC-DDC-Guy]

From your readings, it doesnt sound like an N2 failure. That bus is pretty robust, especially with those controllers.
Are there XT or XP modules attached to any of these DX's? Do they have different addresses than anything on the N2 bus?
Did you plug your converter right into the DX's N2 port and check the comms?
Do you have the addressing right?
Did you try the bus scan with HVAC Pro? Anything new show up?
Are the three that are offline together or in different parts of the bus?

If you have HVAC Pro on the front end (PMI) you can scan the bus from there. Scan it and see if you get some DX's with different addresses. If you have XP's or XT's, make sure their addresses are unique.
You can also use your converter and scan the DX directly with HVAC PRO and see what shows up.
If all these fail, then it sounds like you had a weird problem and need to change some DX's. Before you do, check for ground loops in your N2 bus.

[Koluib]

There are no XP or XT Modules.
Yes I check very carefully DX's N2 port for communication.
As there is no password and restriction and I change Addresses so I think I have right to add or remove any sensor etc.
Yes I try with HVACPRO,and scan the Bus,Offline controlles not appear in List.
Offline controllers are at different locations on same Bus.
Yes I tried to communicate with Converter directly and get communication failure and then I remove converter and put Serial cable at Rs232 and it is communicating,uploading Downloading,changing values I mean everything normal.Yes it is weird problem therefore I give trouble to you guys.I am thankful to everyone who try to help.

[freddy-b]

Well, then you must just have a total break in the N2. Do you have a repeater on the trunk? Repeater working/powered?

Unplug the N2 at all 3 DX's at the same time. and see if you have any voltage on the wires. If you have no voltage then you are not physically connected to the rest of the trunk...via a physical break or repeater malfunction.

[Koluib]

Well, then you must just have a total break in the N2. Do you have a repeater on the trunk? Repeater working/powered?

Unplug the N2 at all 3 DX's at the same time. and see if you have any voltage on the wires. If you have no voltage then you are not physically connected to the rest of the trunk...via a physical break or repeater malfunction.

Yes I mentioned in previous post that there are 2 to 2.2 voltage fluctuating between Ref & Pos and Ref & Neg.There is no repeater.I think it is not Bus problem,if it was Bus then at least DX must communicate with converter because it is Direct,But these controllers are not communicating indivdually through N2(RS485)ports but with Serial ports(RS232) they all are communicating individually.I don't know if somebody knows Electronic Hardware side to catch the problem.Thank you.

[HVAC-DDC-Guy]

Yes I mentioned in previous post that there are 2 to 2.2 voltage fluctuating between Ref & Pos and Ref & Neg.There is no repeater.I think it is not Bus problem,if it was Bus then at least DX must communicate with converter because it is Direct,But these controllers are not communicating indivdually through N2(RS485)ports but with Serial ports(RS232) they all are communicating individually.I don't know if somebody knows Electronic Hardware side to catch the problem.Thank you.

Koluib,
You have set across a problem that I have not encountered. Additionally, I have serveral JCI solutions CDs that have not encountered this problem. This is a strange one.
If you are a customer, I would call JCI and see what they come up with.
You seem to have covered all of the bases. The voltages across the bus seem acceptable and if they are modulating, then the 485 bus is working.
Address switches would not be a problem with all three at the same time.
Whatever you find out, pay close attention to the anomally that may have caused it. Let us know what you find out.

[freddy-b]

Yes I mentioned in previous post that there are 2 to 2.2 voltage fluctuating between Ref & Pos and Ref & Neg.There is no repeater.I think it is not Bus problem,if it was Bus then at least DX must communicate with converter because it is Direct,But these controllers are not communicating indivdually through N2(RS485)ports but with Serial ports(RS232) they all are communicating individually.I don't know if somebody knows Electronic Hardware side to catch the problem.Thank you.

What I am saying is , if the section of bus that you can not read has any device connected to the N2 you will see voltage at any one of them as long either of the others are connected. If you disconnect all three from trunk and still have voltage then you know for sure that you are actually connected to the known working bus. If you have no voltage with all three disconnected then you know they are isolated by a break.
the 232 port has absolutely nothing to do with N2 communications.
Can you expalin directly connecting with 485! Directly to the N2 at the NC with the nc disconnected from bus. Or at the DX itself?
If you can not connect directly at the DX with the 485 converter and you have swapped with a known good one, then it really it can only be that the backplates are bad.

[NINAX]

Same problem where? The same controller or the same location?

I never saw this answer, so once again.

[foyler]

DX were Swap in different locations with new jumper settings and new addresses,but the same controllers are problamatic at every location.Once NCM power supply was blown some times before.But 75% controllers are communicating normal.

Sounds to me like those controllers need to be replaced.

[NINAX]

Sounds to me like those controllers need to be replaced.

He's never answered if the problem traveled with the DX or stayed with the location.
I'd say, with the vagueness of the provided info, it may be a bit premature to make that call.