User`s manual

MGate MB3000 User’s Manual Configuring the Modbus Gateway
4-9
Serial Settings
Parameter Value
RS-232
RS-422
RS-485, 2W
Interface Mode
RS-485, 4W
Baud Rate 50 bps to 961200 bps
Parity None, Odd, Even, Space, Mark
Data Bits 7, 8
Stop Bits 1, 2
Flow Control None, Xon/Xoff, RTS/CTS
UART FIFO Enable, Disable
Set up Slave ID Mapping (Smart Routing)
The SID Map tab is where slave IDs are managed. The definitions on this tab determine how
requests will be routed by the unit.
What Mapping Does
According to the Modbus protocol, all slaves in a network must have a unique ID between 1 and
247, which is used to indicate the intended recipient of a request. Therefore, a slave ID is
incorporated into the design of every slave device, regardless of manufacturer, and is usually (but
not always) configurable. This is the “actual” slave ID, which is wired or programmed into the
device itself.
On the MGate MB3000, a “virtual” slave ID is assigned to each device that will be accessed
through the gateway. Any Modbus master that sends a request through the gateway must identify
the intended recipient using the virtual slave ID rather than the actual slave ID. The parameters in
the SID Map tab will be used by the MGate to route the request to the correct device.
The ID table is what makes smart routing possible for units with multiple serial ports. With proper
configuration of the ID table, TCP master commands are sent directly to the serial port holding the
device, rather than broadcast to all serial ports. Smart routing keeps communication efficient and
prevents devices on one port from slowing down the whole system.
ATTENTION
Any slave device that is not assigned a virtual slave ID in the SID map will not respond to any
requests that come through the MGate MB3000.
How ID Table is Defined
In the ID table, you specify a range of virtual IDs to be routed to an IP address or serial port. If the
virtual ID is different from the actual ID, you will also specify the offset value that will be used to
obtain the actual ID.