Setting Up and Connecting MEXM Units in TCP Mode

Setting up a MEXM in TCP mode

Set the TCP/RTU communications-mode selector switch to position 0 to configure a MEXM for TCP. The default parameters for the MEXM are shown in the table below.

IP Address
Subnet Mask
Default gateway
IP port 502

Default MEXM IP parameters

Connecting MEXM units in TCP mode

The DV-208, DV-216 and DV-Mini units support the Modbus protocol only on the RJ45 Ethernet Jack 2. This connector should always be used to connect a MEXM to the Davicom unit. The DV- Micro Ethernet jack fully supports the Modbus protocol.

Connecting one MEXM in TCP mode

To connect a single MEXM to a DV-208/DV-216 or a DV-Mini, use the crossover Ethernet cable provided with the MEXM. Connect the cable between the Davicom unit RJ45 Ethernet Jack 2 and the MEXM RJ45 Ethernet jack as shown in the two images below.

MEXM to DV-Mini TCP mode connection (crossover)
MEXM to DV-208/216 TCP mode connection (crossover)

Connecting more than one MEXM in TCP mode

Connecting a MEXM to a Davicom unit via an Ethernet switch or an existing network infrastructure requires the use of a straight Ethernet cable (not included with the MEXM).

It is preferable to use a separate switch for connection between the MEXM units and the Ethernet 2 jack on the Davicom (see image below). This will reduce the possibility of loosing communications between the Davicom and the MEXM. Although a single network router/switch configuration at the site will work correctly, the increased IP traffic may slow down communications between the Davicom and the MEXM modules, thus resulting in COMM LOSS alarms. Reducing the sensitivity from High to Medium or Low may help under these conditions (see this article).

Connecting more than one MEXM in TCP mode
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