Echelon DM-21 Device Manager - Manual (Page 13)

Device Manager User’s Guide 1-9
If a newly discovered device matches an existing device that has already been
discovered, the existing device will be pinged to see if it is still operating and has
the correct location string. If it does, the newly discovered device will be ignored.
If not, then the existing association of logical and physical device will be removed
and the newly found device will be commissioned and added to the Managed
Device List.
A device with an unknown Program ID will not be discovered; if found on the
network, the device will be ignored, and no report made. However, devices with a
known Program ID and an unknown location string will be discovered. If on a
subsequent discovery operation the location string has changed to a known value
(say due to configuration by a handheld tool), then the Device Manager will
consider the device a new device and will discover it.
Automatic Commissioning
Automatic commissioning takes place if the device’s Program ID and location
string are known and the auto-commission bit in the Managed Device List is set.
By default, all devices have their auto-commission bit set. Echelon does not
support alternative uses of this bit.
Pinging Devices
Devices that have been commissioned are periodically pinged. Pinging consists of
sending a query status diagnostic message and reading the device’s location
string. The Device Manager will then validate the device state, subnet/node
address, and location string as follows:
• If the device fails to respond to a ping after the defined number of ping
retries, the Neuron ID in the Managed Device List will be deleted, breaking
the association between that device and the corresponding record in the
Managed Device List. The
DMEVNT_MISSING
event will be logged in the
Device Manager’s internal event log and this value will be sent on the
DM_Event network variable if its Async bit is set.
• If the device fails to respond to pinging and another matching device is
discovered, the Neuron ID of the old device will be immediately deleted from
the Managed Device List. The
DMEVNT_MISSING
event will be logged in the
Device Manager’s internal event log and this value will be sent on the
DM_Event network variable if its Async bit is set. This is the same as above,
except that a single failure causes this to occur since there is already a
possible replacement.
• If the device’s location string does not match the one in the Managed Device
List, the Neuron ID will be immediately removed from the Managed Device
List. The
DMEVNT_MISSING
event will be logged in the Device Manager’s
internal event log and this value will be sent on the DM_Event network
variable if its Async bit is set. The physical device corresponding to the
Neuron ID will be treated as though it is newly discovered.
• If the device’s location string matches the location string in the Managed
Device List, and the state is incorrect (but not applicationless), a
DMEVNT_CONFIG_ERROR
event will be logged in the Device Manager’s
internal event log and this value will be sent on the DM_Event network
variable if its Async bit is set. The device will be re-commissioned.