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.