Hardware Overview
Manual Documentation Number: MES1A/MES1B-2106m PN7138-rev001
B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104 – www.bb-elec.com
B&B Electronics Ltd – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph +353 91-792444 – Fax +353 91-792445 – www.bb-
europe.com
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RS-422/485 Switch (MES1B only) The RS-422/485 switch allows you to set the MES1B Converter for
RS-422/485 four-wire or RS-485 two-wire operation.
• When the switch is in the left position, the MES1B operates in
RS-422/485 four-wire mode.
• When the switch is in the right position, the MES1B operates
in the RS-485 two-wire mode.
Ethernet Port Connector The Ethernet P ort connector is a standard RJ-45 receptacle that
allows the converter to be connected to an Ethernet network. Two
indicator LEDs (described above) are built into the RJ-45
connector.
DB-9M Serial Port Connector (MES1A only) The Serial Port Connector on the MES1A is a DB-9 male
connector (configured as a DTE) supporting RS-232 serial
communications including TD (Pin 3), RD (Pin 2) and GND (Pin 5)
signal lines. If the Modbus device you are connecting to the
MES1A is configured as a DCE you will use a straight-through
serial cable. If the Modbus device is configured as a DTE, use a null
modem cable.
Refer to Appendix D for connection pin-outs.
RS-422/485 Connector (MES1B only) The RS-422/485 connector on the MES1B is a five position
removable terminal block with screw downs. The connector
provides screw connections for:
• Terminal 1 - RDB(+)
• Terminal 2 - RDA(-)
• Terminal 3 - TDB(+)
• Terminal 4 - TDA(-)
• Terminal 5 – Ground