Moxa CP114EL-I Serial line adapter
The Processor Unit is equipped with a Moxa CP114EL-I serial adapter board. The serial adapter offers four serial ports. The serial lines are provided as a large D-Subminiature connector on the rear side of the computer.
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The Moxa CP114EL-I serial adapter supports RS-232, RS-422 and RS-485 (both 2 and 4-wire). The connections to the board are made using a converter cable with four 9-pin male D-subminiature connectors. The converter cable is supplied with the Processor Unit.
•  ManufacturerMoxa
•  Manufacturer’s website: https://www.moxa.com
Unless otherwise specified, this cable must be provided by the installation shipyard. If you wish to use RS-422 or RS-485 serial communication, use a cable with twisted pairs.
Note
Observe that long runs of unshielded cable will pick up noise easily. This is because the RS-232 signals are not balanced.
Maximum length for an RS-232 serial cable is typically 60 meters with 2400 bps data rate, however this depends on the cable quality. Always check the cable manufacturers specifications for the actual "shunt capacitance". A common figure is 47.5 pF/m, which gives a maximum cable length of about 50 meters.
Even though a standard exist for RS-232 pin configuration, certain manufacturer may still choose their own connector pins for the various signals used. In order to make the RS-232 connection to your peripheral device work properly, you must always consult the relevant instructions provided by the device manufacturer.
Pin configuration
Moxa CP114EL-I connectors / Adapter cable
Pin RS-232 RS-422 RS-485 (4-wire) RS-485 (2-wire)
1 DCD TXD-(A) TXD-(A)  
2 RxD TXD+(B) TXD+(B)  
3 TxD RXD+(B) RXD+(B) Data-(B)
4 DTR RXD-(A) RXD-(A) Data-(A)
5 Ground Ground Ground Ground
6 DSR  -  -  -
7 RTS  -
8 CTS
9   -  -
Minimum cable requirements
•  Conductors2 x 5 x 0.5 mm2
•  ScreenOverall braided 
•  Voltage: 60 V
•  Maximum outer diameterDefined by the plugs and/or the cable gland
If you wish to use RS-422 or RS-485 serial communication, use a cable with twisted pairs. If you need to install a very long cable, increase the cross section.