Specifications
8 UMMBRG300-1101
The Modbus RS-232 connector is a male 9-pin D-sub type located at the bottom side of
the mounted unit (refer to Figure2.1, “Location of connectors”). It has industry standard
EIA-574 data terminal equipment (DTE) pinout as shown in the following table and
picture:
GND
TDX
CTS
DTR
RI
RXD
RTS
1
6
CD
DSR
Pin Signal Function Direction
1 DCD (unused) in
2 RXD Receive data in
3 TXD Transmit data out
4 DTR (unused) out
5 GND Signal ground
6 DSR (unused) in
7 RTS (unused) out
8 CTS (unused) in
9 RI (unused) in
Table 3.2: Modbus RS-232 connector pinout
• Maximum cable length is 15 m (50 ft) or a length equal to a line capacitance of 2500
pF, both at the maximum standard bit rate of 20 kbps. If operating at higher bit rates
the maximum cable length drops to 3 m (10 ft) at a bit rate of 57.6 kbps.
• To assure a high degree of electromagnetic compatibility and surge protection the
RS-232 cable should shielded. The shield shall be connected to an external chassis
ground at the either or both ends, depending on the application.
• The shield must not be connected to the GND pin.
To connect the MBRG-300 to a PC (Personal Computer) or any other device with
data terminal equipment (DTE) pinout you need a null-modem or cross-over cable.
Connecting Ethernet
The following table describes the 10BASE-T Ethernet RJ-45 connector pinout:
TX+
TX-
RX-
RX+
1
Pin Signal Function
1 TX+ Non-inverting transmit signal
2 TX- Inverting transmit signal
3 RX+ Non-inverting receive signal
4 Internal termination network
5 Internal termination network
6 RX- Inverting receive signal
7 Internal termination network
8 Internal termination network
Table 3.3: Ethernet connector pinout
• We recommend to use Category 5 UTP network cable.