Comtrol C53 User Manual
Page 10
Impedance Matching and Termination Resistors
10
Impedance Matching and Termination Resistors
When an electrical signal travels through two different resistance junctions in a transmission line, the mismatch will sometimes cause
signal reflection. Signal reflection causes signal distortion, which in turn will contribute to communication errors. The solution to this
problem is to establish the same impedance at the RS-485 line ends as in the line itself by terminating them with resistors.
Comtrol manufactures the converter with jumpers to enable and disable termination resistors. To set the jumper, remove the two screws
in the cover and set the jumper to cover both pins.
Troubleshooting
If installation fails or you are trying to resolve a problem, you should try the following before calling the Comtrol technical support line:
For data transmission failure:
•
Check that you are using the correct power adapter.
•
Check that switches 1 and 2 are properly set.
For data loss or error:
Check that the data rate and data format are the same for both devices
Self Test
This configuration is for C52/C53 self test. Run the terminal emulation program to see if what you received is what you typed.
In the graph, TxD A, TxD B, RxD A, and RxD B could be either from RJ45 or the terminal block.
FCC Notices
Radio Frequency Interference (RFI) (FCC 15.105)
This equipment has been tested and found to comply with the limits for Class A digital devices pursuant to Part 15 of the FCC Rules.
This equipment generates, uses, and can radiate radio frequency energy, and if not installed and used in accordance with the instruction
manual, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a
particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by
turning the equipment off and on, the user is encouraged to try and correct the interference by one or more of the following measures:
•
Reorient or relocate the receiving antenna.
•
Increase the separation between the equipment and the receiver.
•
Connect the equipment to an outlet on a circuit different from that to which the receiver is connected.
•
Consult the dealer or an experienced radio/TV technician for help.
Labeling Requirements (FCC 15.19)
This equipment complies with Part 15 of FCC Rules. Operation is subject to the following two conditions:
•
This device may not cause harmful interference, and
•
This device must accept any interference received, including interference that may cause undesired operation.
Modifications (FCC 15.21)
Changes or modifications to this equipment not expressly approved by Comtrol Corporation may void the user’s authority to operate this
equipment.
Serial Cables (FCC 15.27)
This equipment is certified for Class A operation when used with shielded cables.