8
D. PARITY AND STOP BITS
The parity/stop bits parameter of the Modbus adapter must be set to match the rest of the devices on the bus. Although it is common to
set serial devices to use no parity, setting the parity to even or odd may improve communications reliability on all connected devices on
the bus.
This parameter has 4 possible selections which should be sufficient to establish communication with other devices. These selections
are outlined in Table 4.
Parameter
Setting
Description
40
0
No parity 1 stop bit (factory default)
40
1
No parity 2 stop bits
40
2
Even parity 1 stop bit
40
3
Odd parity 1 stop bit
Table 4
– Parameter 40 Settings
Press and Hold the
RESET
button to store all parameters and exit the Installer Menu.
PART 4 – COMMUNICATION CONFIGURATION (APPLIANCES WITH AN LCD TEXT
DISPLAY)
A. MODBUS ENABLE
1. Press and hold the
ENTER
key until you see the screen at right.
Use the
RIGHT
arrow to select a character, then use the
UP
and
DOWN
arrows to
select the desired character value.
RIGHT
arrow over to the next character and repeat the selection. Once you have 925 on the screen,
press and hold
ENTER
on the display to enter the Installer Menu.
2. Once in the Installer Menu, use the
RIGHT
arrow to navigate to Parameter 37. When at Parameter 37, press
ENTER
. The current
setting should be flashing. Press
UP
or
DOWN
to select the desired setting from Table 5:
Parameter
Setting
Description
37
OFF
MODBUS “DISABLED” (factory default)
37
ON
MODBUS “ON”
37
AUTOMATIC
MODBUS “AUTO” (enables automatic detection of a PC or Adapter)
Table 5
– Parameter 37 Settings
FUNCTION 37
Press
ENTER
once the desired setting is flashing on the display. Once accepted, the
selection should not flash.
Please do not leave the Installer Menu. Configure the Address, Baud Rate, and Parity settings described below.
B. MODBUS ADDRESS
NOTE:
Modbus must be enabled on the appliance as outlined above for the following parameter to be viewed and changed.
The Modbus address space is comprised of 256 addresses. These are defined as follows:
Address 0 is a broadcast address. The master can send data to address 0 and all followers will process the data.
Addresses 1
– 247 are free to be assigned to Modbus devices on the bus. Each address can be assigned to only one Modbus
device on the bus.
Addresses 248
– 256 are not available for use.
MODBUS ADDRESSING SUGGESTIONS*
Each device must have a unique address.
It is not recommended to use 1 as an address, as this is often the default address for various Modbus devices.
In order to keep track of addresses for future maintenance purposes, record all device addresses in the Installation
and Maintenance Notes section, included in this manual.
*SAVE THIS DOCUMENT IN A SECURE LOCATION FOR FUTURE REFERENCE.
In the Installer Menu, press
RIGHT
to advance to Parameter 38.
FUNCTION 38
Press
ENTER
. The address value will blink. Use the UP and DOWN arrows to set the
desired address. Press ENTER again to accept your selection (and stop the display from
ENTER MENU CODE
925
MODBUS MODE
OFF 37
MODBUS ADDRES
0 38
