KMD

[agross]

I am working on a Kreuter system appx 10yrs old. One of the many problems I am having is that 5 to 6 panels on the Sub A buss intermittently show offline. When I went to one of the panels I found it to be the last panel on the physical buss; meaning that there is only a pair of wires terminated on the A and B terminals. In looking at the EOL pins, there are no jumpers. This is not the highest addressed panel, and the software setting has been verified in the highest panel. I have two questions, since this is the EOL panel how should the jumpers be placed? The panel is a KMD 60011704 VAV controller. The pins are in a 2x2 square configuration with the fuse/lamps to the right (looking at the controller w/ the damper actuator to the left). Additionally, are the lack of the EOL jumpers my source of the interment panel losses, or am I battling EMI or some other problem. Thanks for the help.

[kgesper]

M first question would be are you certain about that model number? The KMD 6001 didn’t use EOL jumpers it used dip switches. Dip switches 4 & 5 should be labeled A & B on the 5 dip switch row. (They should be on, flipped toward the actuator). Dip switches 1, 2 & 3 are the pull up resistors for the inputs.

As far as the network communication issues it could be a number of things. Are there any repeaters on the network? There needs to be one every 32nd controller. The network length should not exceed 4000 feet. The 6000 series controllers used to be shipped with the EOL jumpers on. When setting up the network you needed to place these in the off position on every controller except for the physical end of line. It was a common mistake to not change these so the network signal ended up getting shunted at every controller. The network voltages are measures from A to ground and B to ground. On a healthy network you will have 2.4 and 2.6 VDC at these terminals.

And of course as you mentioned EMI, ground loops, loose connections, weak comm. chips, and many other factors will affect communications adversely. A good RS-485 tracing software that shows you the token being passed from one controller to the next is also a valuable troubleshooting tool. KMC has there own called LAN Monitor. I hope this helps and good luck.

[kgesper]

I just found out from one of our engineers that some of the early KMD 6001’s did have jumpers. When KMC switched from through hole mounted components to surface mounted components on their circuit boards, the dip switches were added. The jumpers need to be placed parallel to the length of the screw terminal strip. The rest of the information above is correct.

[controldude]

I agree with kgesper also on the old version boards instead of pull up resistors you hadd to cut the resistors if your application required so. I used to have a copy of analyzer software made by CW Industries but my hard drive crashed I don't know if you can get this from them due to all passwords come up also.

PS any one board that shorts out can cause the same problem and that can be a hard one to find.

[agross]

Thanks for the help. I called around the other day, and one guy suggested ohming between the pins and the A and B terminals, and then between the pins. In doing this I found one had continuity to A, one to B and the other two had a resistance value between them. Needless to say, the jumpers ended up going on parallel to the terminal block. This helped a little bit; then I found a loose buss connection on another controller, that helped a lot. Still, the A buss bounces offline occasionally, not nearly as often. When I was backing up the pan files on my laptop, there was one controller that would not back up. I can see the inputs and outputs on it, but I can't open up the programs or trend logs. I think I may pull that one off the buss and see what happens. Thanks again for the help.