B&B Electronics MES1A - Manual (Page 35)

Configuring the MES1A/B
Manual Documentation Number: MES1A/MES1B-2106m PN7138-rev001
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• the Serial Interface type and communications parameters
Figure 17. Serial & Mode Settings Menu
To configure Serial and Mode Settings, type 2 at the Select Command or
parameter set (1..4) to change: prompt. The Attached Device
prompt appears.
Protocol
Protocol parameters must be set to match the type of Modbus device (master
or slave) connected to the serial side of the MES1A/B device, and the type of
Modbus protocol (ASCII or RTU) that will be used.
Attached Device
Modbus devices operate as either Masters (polling Slaves) or Slaves
(responding to polls from Masters). An example of a Modbus master is a
computer running HMI (human machine interface) software. Examples of
Modbus slaves are controllers, remote terminal units (RTU) or programmable
logic controllers (PLC).
To configure the type of Attached Device:
25. At the Attached Device (1=Slave 2=Master)(1) prompt
o To keep the current setting, press Enter
o To select Slave, type 1
o To select Master, type 2
26. To accept changes, press Enter
Note: When Master mode is selected a fifth item (Unit ID -> IP Address Table is
added to the Configuration Menu.
Serial Protocol
Modbus devices communicate in either of two Serial Protocols: ASCII or
RTU. Modbus/ASCII protocol is slower and uses two ASCII characters to
represent each 8 bit data byte. Modbus/RTU uses 8 bit binary data characters.