Alliance Laundry Systems NK101 - Manual (Page 19)

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Troubleshooting
© Copyright, Alliance Laundry Systems LLC – DO NOT COPY or TRANSMIT
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.
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.