APPENDIX E Receiver Card Interface Examples
OEM7 Installation and Operation User Manual v4
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E.3 Communication Ports
The COM ports on OEM7 receivers (except COM1 on the OEM729) are CMOS-level I/O pins only.
These ports require the addition of an RS232 or RS422 transceiver to provide appropriate signal
levels. Most RS232 or RS422 transceivers will provide some ESD protection (for harsh envir-
onments, additional protection may be required).
COM1 on the OEM729 uses RS-232 protocol by default. This port can be changed to RS-
422 protocol using the
SERIALPROTOCOL
command.
A combination of a series ferrite bead and small-value shunt capacitor is recommended on any
RS232/RS422 lines that leave the enclosure (similar to the arrangement used on the I/O ports
and CAN interfaces). Many of the available transceivers provide protection for ESD events to
±15kV – if additional protection is required, an external TVS with a working voltage of ±15V to
±25V will be required.
