QUANTUM
™
LX EVAPORATOR CONTROL PANEL
COMMUNICATIONS SETUP
090.610-CS (MAY 2016)
Page 44
MODBUS® Data Access
Data passed to and from the Quantum™ are integer
values with one decimal eld assumed unless shown
otherwise or the command is sent to select two deci-
mal elds. For example, if the data’s value is 25.5 then
the value 255 is sent. All temperatures are in degree C
and all pressures are in PSIA unless the command is
sent to select the units of the panel. A mode such as
Slide Valve mode is sent as an integer value that rep-
resents the mode it is in. For example, a 0 is sent if it is
in manual, or a 10 is sent if it is in automatic, or a 20 is
sent if it is in remote. The value zero (0) is used to rep-
resent an OFF status and a DISABLED option. The value
one (1), which is received as a 10, is used to represent
an ON status and an ENABLED option. Only data values
that are designated as setpoints are modiable. Read
Only is used to help identify what data is not modi-
able. The setpoint range is checked to see if it is an
allowed setting. If it is not allowed, the setting is not
changed. Reference the Quantum™ Data Tables in this
manual for the address listing and description of data.
A command has been provided that selects whether
data to and from the Quantum™ will be returned in the
units that are the default (pressure in PSIA and tem-
perature in Degree C) or in the units that are selected
to display at the panel.
MODBUS® NOTES
This has been an example of how the Quantum™ Con-
troller uses the MODBUS® Protocol. It is hoped that
the information provided here will assist the end user
in writing applications that will allow the Quantum™ to
be implemented into networks that the customer may
already have in use.
This information is subject to change at any time, and
is provided as a reference only. Not all areas of the
MODBUS® Protocol can be handled in this document.
Some additional information regarding MODBUS®
Protocol that the end user should be aware of:
• There are many versions of MODBUS® Protocol
that are available, and an application that works
properly on one system, may not function identi-
cally on another.
• Some versions of MODBUS® Protocol may require
the user to increment any referenced addresses
by 1 (one). For instance, if you wanted to look at
Frick® Address 2003, you may need to actually
look at address 2004. The Quantum™ addressing
begins at 0 (zero), whereas some MODBUS® Pro-
tocols begin at 1 (one), therefore, you may need to
compensate.
• 7 or 8 bits selectable.
• 1 or 2 Stop bits selectable.
• Parity can be set to None, Odd or Even
• When using MODBUS® protocol (other than the
Hyperterminal example shown earlier), it is nec-
essary to use the MODBUS® Address column as
shown in the Quantum™ Data Tables. These ad-
dresses should work for most applications.
• Follow the Frick® specications for data commu-
nications requirements.
• Hyperterminal can be used to test ASCII, but not
RTU or TCP/IP communications.
NOTE: Be careful not to continuously request a set-
point change. It is to be expected that communica-
tions may slow down during the process of writing
setpoints or clearing alarms. Both of these pro-
cesses involve writing to either EEPROM or Flash
Memory and does take some time. If communication
requests are being sent faster than once every cou-
ple of seconds, there will be temporary slowdowns
during these processes.
To Next Page
Loading...
