Alliance Laundry Systems NK100, NK101, NK120 Network Interface Boards

Network Interface Boards

Wire Break - Any time there is a wire break on the network, all machines on the opposite side of the break from the Central PC will become unable to communicate with the Central PC. Also, communication may become less reliable for those nodes which are still on the network, since the terminating resistor on the end of the network has been separated from the network.

Short on the Line or on the Network Board - If there is ever a short on the network, the entire network may be unable to function. However, if the short is on the far end of the network, those nodes closest to the Central PC may be able to communicate with the Central PC to some degree.

Shorts may be isolated by removing the RS-485 cable from the PC, and putting an Ohm-meter on the cable. Next, remove a series of machines at the end of the network, and check the meter. If there is no longer a short, the short is somewhere in the chain of machines removed from the network. If there is still a short, move the break in the network close to the Central PC until a location is found where the short can be eliminated. By repeating this process of elimination, a short in either the cable or on a network board may be isolated.

Wires Flipped on the Network - Correct polarity must be observed when installing machines on the network. If a machine is installed with the wrong polarity at either the input or output (but not both) at the connecting terminals, all machines further down the series will be unable to communicate with the Central PC. If, however, both the input and output are wired incorrectly, only that machine will be unable to communicate. If the wires at the card on the PC are flipped, none of the machines will be able to communicate with the Central PC.

NOTE: Both shorts or flipped wires will cause numerous errors on the central PC, including “Protocol Errors” and numerous “Unable to Connect” messages.

Troubleshooting

Nodes on the Same Address - If two or more nodes share the same address, there will be intermediate levels on the network, which may be observed with an oscilloscope. These intermediate levels will occur whenever the Central PC commands a response from the address at which there are multiple nodes. In most cases, the Central PC will not be able to communicate successfully with any of the devices at this address. In some cases, however, if two nodes share the same address with one close to the Central PC and the other on the opposite end of the network, the node closest to the PC may be able to overpower the other, and complete a valid communication. The one at the far end, in this case, will not be able to communicate at all with the Central PC.

NOTE: Nodes on the same address will cause numerous errors on the central PC, including “Protocol Errors” and numerous “Unable to Connect” messages.

Jabbering Node - In this condition, a node on the network is transmitting erratically. If the node is transmitting constantly, this condition may bring down the entire network. In other cases, it may transmit periodically. If this is the case, some communications will be able to get through, until the node begins jabbering again. A jabbering node may be detected by disconnecting the network from the PC and monitoring the network with an oscilloscope. Since the PC initiates all communications, the scope should show no communications once the PC is removed. If the scope indicates that there is communication occurring, individually remove each node from the network and use the scope to check for communication from that node.

NOTE: Jabbering nodes will cause numerous errors on the central PC, including “Protocol Errors” and numerous “Unable to Connect” messages.

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