Pin
Parameter
Description
Pin 9
RS-232 Tx
Serial RS-232 connection. This bus must use a ground connection between devices to operate
correctly. (DXM100-B1 models only; not available on the DXM100-B2 models)
Pin 10
RS-232 Rx
Pin 13
Secondary RS-485 –
The DXM100-Bx Wireless Controller is a Modbus slave on this bus (see
on page 19).
Pin 14
Secondary RS-485 +
Pin 15
CANL –
DXM100-B1 models only. Not available on the DXM100-B2 models.
Pin 16
CANH +
6.4.1 Modbus RTU Master/Modbus RTU Slave
The DXM100-Bx Wireless Controller can be a Modbus RTU master device to other slave devices and can be a Modbus slave
device to another Modbus RTU master.
The DXM100-Bx Wireless Controller uses the primary RS-485 port as a Modbus RTU master to control external slave
devices. The secondary port is the Modbus RTU slave connection.
•
As a Modbus RTU master device, the DXM100-Bx Wireless Controller controls external slaves connected to the
primary RS-485 port, the local ISM radio, local I/O base board, and the local display board.
•
As a Modbus RTU slave device, the DXM100-Bx Wireless Controller local registers can be read from or written to by
another Modbus RTU master device.
Use the DXM Configuration Tool to define operational settings for both the Modbus RTU master port and the Modbus RTU
slave port.
6.5 Modbus Master Port and Slave Port
There are two RS-485 ports on the DXM Controller, a Modbus master RS-485 port and a Modbus slave RS-485 port.
The Modbus master RS-485 is controlled by the DXM Controller, which acts as the Modbus master. All wired devices
connected to the master RS-485 port must be slave devices.
The Modbus slave RS-485 port is controlled by another Modbus master device, not the DXM Controller. The slave port is
used by other devices that want to access the DXM Controller as a Modbus slave device. All local registers are available to
be read or written from this slave port. Set the Modbus Slave ID for the secondary RS-485 port using the LCD display
menu: System > DXM Slave ID.
6.5.1 Modbus Master and Slave Port Settings
The basic communications parameters for the RS-485 ports are set in the DXM Configuration Tool and are saved in the
XML configuration file. All basic settings are available under Settings > General screen of the DXM Configuration Tool.
Master port parameters include:
•
Baud rate and parity
•
Set the Communications Timeout parameter to cover the expected time for messages to be sent throughout the
wireless network. For the DXM Controller, the Communications Timeout parameter is the maximum amount of
time the DXM Controller should wait after a request is sent until the response message is received from the Modbus
slave device.
•
Maximum Polling Rate sets the minimum wait time from the end of a Modbus transaction to the beginning of the
next Modbus transaction.
DXM100-Bx Wireless Controller Instruction Manual
44
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