Applicable Model(s)

HMI500 Series


Connect HMI500 using Modbus to Ethernet Bridge








With the addition of a Modbus bridge, the Maple Systems HMI500 Series can successfully connect to Ethernet using a Modbus protocol and extended addressing.


One way to allow messages to be passed between Modbus and Ethernet TCP/IP devices is by the installation of a “Modbus to Ethernet bridge.” One such model is the Modicon TSX Momentum 174 CEV 300 10. The bridge functions as a converter between the Ethernet TCP/IP and Modbus RTU protocols. Since the Maple Systems HMI touchscreens support the Modbus protocol, this extra hardware will allow it to be connected to an Ethernet network. Below are the necessary steps for the configuration of the HMI.

Hardware Steps to Connect to Bridge (using RS-232)


Connect a Null Modem to the Maple Systems PLC [RS-232] port.


Using a Maple Systems 232 cable for a Modbus device, connect the cable to the null modem and bridge. There may be a diagram in the bridge manual.

Hardware Steps to Connect to Bridge (using RS-485)


Follow the RS-232 steps using the Maple Systems PLC [RS-485] port and 485 cable.

Software Steps


Select the Modbus RTU protocol or the Modbus RTU Extend V3 protocol under Edit, System Parameters, PLC type. Change the communication parameters (Baud Rate, Parity, Stop Bits, etc.) to match those of the bridge.


Set the HMI for Extended Addressing. Go to Edit, System Parameters, and then click on the Editor tab. Change Address Mode to read “Extended.” This now allows reference to a range of 256 PLC Station numbers. To specify station numbers use the following syntax for entering addresses into the Address field of the Attributes dialog box:

Station Number#Register Address

NOTE: The Station Number and PLC Register Address are separated by a pound sign (ASCII 35). For example, address 40100 in the PLC whose station number is 5 would be entered as:

Device Type: 4x

Device Address: 5#100

Configure the Bridge

Reference the bridge manual.

More Information

For more information regarding Ethernet connections, please reference your bridge manual or
contact Maple Systems Technical Support.

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