Ethernet Serial Server – MESR900 Fibre

  • Ethernet enable Modbus RS-232/422/485
  • Modbus TCP, ASCII & RTU
  • Modbus flexibility – serial & Ethernet, Masters & slaves
  • Modbus messaging priority control
  • View messaging status in real time
  • Easy configuration software


MESR921-MC Modbus Gateways bridge devices on Modbus serial networks (RS-232, RS-422 or RS-485) with those on Modbus TCP networks, allowing seamless integration. Serial ports can be accessed over a LAN or WAN using Direct IP Mode connections. Supporting up to 16 masters and 32 slaves, these gateways feature auto-detecting 10/100 copper and fibre optic options. Easy-to-use software is designed for Windows 2000, 2003 Server, XP, Vista, 2008 Server and Windows 7. Serial data rates up to 230 kbps ensure maximum network flexibility. MESR92x gateways are built for use in industrial environments, featuring a slim IP30 DIN rail mountable case. They operate from a range of DC power supply voltages and have pluggable terminal block connectors. An external power supply, sold separately, is required. The units have an additional Ethernet port which functions much like an Ethernet Switch, allowing pass-through connectivity for other Ethernet devices. This port can also be used to “daisy chain” multiple gateways.

Part Number Serial Ports Serial Connectors Ethernet Ports Ethernet Connectors
BB-MESR921-MC 1 DB9 or Terminal Block Multi-mode Fibre, Copper (1) SC, (1) RJ45
Serial Technology
RS-485 2-Wire Data A(-), Data B(+), GND
RS-422/485 4-Wire TDA(-), TDB(+), RDA(-), RDB(+), GND
Serial Connector 62.5 / 125 µm
Connector DB9M or Removable Terminal Blocks, 12 to 28 AWG
Data Rate Up to 230.4 Kbps
Fibre Optic Technology
Type / Wavelength Multi-mode / 1310 nm
Output Power (-) 19 to (-) 14 dBm
Receive Sensitivity ~ (-) 32 dBm
Cable 62.5 / 125 µm
Connector SC or ST
Range 2 km (1.2 miles)
Source External
Input Voltage 10 to 48 VDC (58 VDC Maximum)
Connector Removable Terminal Block (12 – 28 AWG)
Power Consumption
MESR92x 6.0 Watts
LED Indicators Serial Port, Ethernet Link, Ready
Switches Reset Button
Dimensions MESR92x: 14.86 x 10.11 x 2.96 cm (5.85 x 3.98 x 1.16 in)
Enclosure 35mm DIN mount, Plastic, IP 30
Weight MESR92x: 0.45 lbs (201.4 g)
Operating Temperature -40 to 80°C (-40 to 176°F)
Operating Humidity 0 to 95% Non-condensing
MTBF ~ 102593 hours
MTBF Calculation Method Parts Count Reliability Prediction
Serial Memory 8 KB per port
Network Memory 4KB
IP Port Addresses 5300 – Heartbeat and configuration
Setting in TCP Mode (paired mode)
8899 – MESR 9xx Update
LAN 10/100 Mbps Auto-detecting
Ethernet IEEE 802.3 auto detecting & auto MDI/MDX 10/100
IP Mode Static, DHCP
TCP/UDP User definable
Mode Modbus RTU Master / Slave
Modbus ASCII Master / Slave
Search Serial direct COM and Ethernet
Auto search or specific IP
Diagnostics Display PC IP, ping, save test config. (text readable)
Firmware Upgrade Vlinx Manager
Ethernet Pass-Through Port
Standards IEEE 802.3, 802.3u, 802.3x
Processing Type Store and Forward with 802.3x full duplex, non blocking flow control
Flow Control IEEE 802.3x flow control, back pressure flow control
MAC Address Table 2K
Configuration Software
Vlinx Manager Windows 2000, XP (32/64 bit), 2003 Server (32/64 bit), Vista (32/64 bit), 2008 Server (32/64 bit), Win 7 (32/64 bit)
Regulatory / Certifications / Safety
Compliance FCC, CE, NEMA TS2
UL Listed, File E222870
UL Class 1 Division 2 Groups A, B, C, D (HAZLOC)
File E245458

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