COMMISSIONING
The data rate, parity and number of data bits are set using the dual in line switch located above. If a scanner is available the chosen channels and the adjacent channels should be scanned for activity.
With frequency agile products such as the Max and Global a fee channel should be selected as far away as possible from the channel/s in use.
The antenna should be positioned and one modem connected and set to test mode. The scanner should be used to measure the received signal strength. If the strength is > 1uv the link will normally work however a "fade margin" of >10dB is preferable.
If a scanner is not available than once the link has been established plug in attenuators may be used to determine the fade margin.
Finally, once the installation is complete it should be tested for conformance the EMC, Health and Safety and Wiring Regulations etc. Exposed joints should be sealed using
COMMUNICATION PROTOCOLS
RTcom Protocol
The RTcomTM Communication protocol does not make any attempt to correct communication errors. From experience the latency (delay) caused by error correction techniques is prohibitive for the majority of applications. Further the use of a "transmit" buffer imposes a finite file size on the system and hence introduces the need for flow control lines such as DTR. Further, errors can occur in cabling due to induced switching surges, nullifying any error protection on the radio link.
Proprietary Protocols
The majority of our customers use a cable protocol that already employs error checking. This normally comes in the form of a check sum appended to the end of the message. Similarly addressing can be appended to the message giving the destination of the data. Protocols such as Modbus and Eiba Bus handle these functions automatically.
WindowsTM TERMINAL.EXE and HYPER TERMINAL.EXE
WindowsTM depending upon its version contains terminal (Terminal.EXE or Hyper Terminal.EXE) programs that can be used to transfer files between two platforms. From experience we have found the WindowsTM 3.11 version of Terminal.exe to be more reliable than the WindowsTM 95 version. The 98 version has however been improved but performance will vary from machine to machine. The problem we believe with these programmes is the low priority placed on communications by the
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