CTI 2500-RIO-B Installation and Operation Guide V1.4
18
Cable trunk length is measured from the CPU to the most distant base.
CPU
T
T
T
Max Trunk Length
Terminating
Resistor
T = Terminal Block
T
Terminating
Resistor
Figure 6. Trunk Length Measurement
By using a T-configuration as shown in
Figure 7
, the maximum trunk length can be extended to
twice the length shown in the table on the previous page.
T
T
Max Trunk Length
T
T
T
T
Max Trunk Length
T
T
CPU
Terminating
Resistor
T = Terminal Block
Terminating
Resistor
Total Trunk Line Length
Figure 7. T-Connection Trunk Length
Bus termination
In order to minimize cable reflections and ensure a defined noise level on the data lines, the data
transfer cable
MUST
be terminated at both ends with a terminating resistor approximating the
characteristic impedance of the cable. For Belden® 3105A cable, a termination resistor value of 120
ohms should be connected across the TX/RX+ and TX/RX- signal lines.
