User's Manual

July 10, 2002 3-9
CreataLink2 XT Hardware Integrator’s Guide Integration Overview
Environmental Issues
Environmental Issues
The CreataLink2 XT device is designed as an OEM module. Any data transceiver
applications are housed in a host product. The data transceiver has been tested to
environmental specifications that meet the applications of most integrators.
As an integrator, you must meet the following guidelines:
1. The data transceiver must be housed in an enclosure to protect the board
assembly from condensation and water/dust/salt fog intrusion. Any
condensation on board assembly will cause CreataLink2 XT device to be
non-functional.
2. Provide mechanical support of the PCB to withstand drops, transport stress,
and handling.
3. Power supply must be clean per Table 2-1.
4. Ambient air temperature around the CreataLink2 XT device must be
maintained between -40 degrees C and +85 degrees C.
Coasting Performance
Coasting is the process by which the data transceiver remains synchronized to the
ReFLEX network during periods when ReFLEX information (i.e. frames) is not
being received by the data transceiver. The absence of ReFLEX frames can be
caused by the data transceiver being in an RF fade or by the network being
configured to intentionally stop transmitting ReFLEX frames for a period of time.
Synchronization, in this case, has both timing and frequency elements.
Maintaining timing synchronization with the ReFLEX system is critical for both
network and data transceiver operation. When the data transceiver has a message
to transmit into the network, it first informs the network that it has data to send.
The network then schedules the data transceiver transmission and informs the data
transceiver of the specific time to transmit its data. Failure on the part of the data
transceiver to remain very closely synchronized to the network will result in the
transmission occurring at an incorrect time and an increased probability of a failed
message delivery.
Maintaining frequency synchronization is critical for both receive and transmit
operations on the data transceiver. Algorithms deployed in the data transceiver
firmware use received ReFLEX frames for frequency correction. Following the
absence of ReFLEX frames, should the tuned frequency of the receiver drift too far
from the target, messages directed to the data transceiver will not be received.
Moreover, the network will not receive messages transmitted by the data
transceiver if the frequency of the data transceiver transmitter has drifted out of
tolerance.
For a data transceiver in a constant ambient temperature environment, timing and
frequency errors are very small and can be largely ignored. However, in a dynamic
temperature environment, temperature variation of component tolerances can
cause synchronization to be lost. Algorithms in the data transceiver firmware have
been developed to track, predict, and correct both timing and frequency errors
within certain design limits.
A data transceiver in an open air environment (i.e. not in a housing) can maintain
timing and frequency synchronization with the network in the presence of a
temperature gradient not exceeding 1°C/minute. The addition of a housing around
the data transceiver provides an insulating layer which reduces the gradient of the
temperature change experienced by the components on the data transceiver PCB.
It is up to the integrator to select appropriate housing material and thickness, and/