Frick QUANTUM LX AcuAir Manual Download Page 37

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FRICK

QUANTUM™ LX AcuAir

CONTROL PANEL S90-510 CS (MAR 07)

COMMUNICATIONS SETUP Page 37

properly on one system, may not function
identically 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 135, you may

need to actually look at address 136. The
Quantum™ addressing begins at 0 (zero),
whereas some MODBUS

Protocols begin at 1

(one), therefore, you may need to compensate.

•

Follow the Frick



specifications for data

communications requirements.

RTU Query (Read) Example

(NOTE: Hyperterminal cannot be used to test RTU):

In the following example, a MODBUS

command is sent to

obtain the actual Room Pressure. Refer to the following
example to see what this message packet would look like:

Start

Addre

Functio

Startin

Addre

# of

s to

Load

CRC

End

T1-T2-T3-

01 03

01 *

T1-T2-T3-

* The CRC value is calculated by the transmitting device,
which appends the CRC to the message.

RTU Response Example

Using the RTU Read example just shown, a typical
response would look like:

Start Address

Function

Byte

count to

Answer

CRC

End

T1-T2-T3-T4 01

02 04 23 * *

T1-T2-T3-T4

The returned value in the above example is 0423 hex.
Converting this to decimal equates to 1059, and assuming
a decimal point gives an answer of 105.9 (PSIA or Panel
units, depending on which has been selected).

MODBUS

NOTES

•

7 Data bits are used for ASCII

•

8 Data bits are used for RTU.

•

1 or 2 Stop bits may be used.

•

Parity can be set to None, Odd or Even

•

When using MODBUS

protocol (other than the

Hyperterminal example shown earlier), it is
necessary to use the MODBUS

Address column

as shown in the Quantum™ Data Tables. These
addresses should work for most applications.

•

Follow the Frick

specifications for data

communications requirements.

•

Hyperterminal can be used to test ASCII, but not
RTU or TCP/IP communications.

•

When using MODBUS

TCP, use port 502.

•

When using Modicon Setup Software, ensure
that:

•

Head Number = Rack Position (position of
Ethernet card in its rack)

•

Map Index = Quantum physical ID number

•

Socket # = 502

NOTE: Be careful not to continuously request a setpoint
change. It is to be expected that communications may
slow down during the process of writing setpoints or
clearing alarms. Both of these processes involve writing to
either EEPROM or Flash Memory and does take some
time. If communication requests are being sent faster than
once every couple of seconds, there will be temporary
slowdowns during these processes.

MODBUS

DATA ACCESS

Data sent to and from the Quantum™ consist of numbers
having one decimal place. For example, if a data value of
25.5 must be transmitted as a 255.

By default, all temperature and pressure values are
transmitted as degrees C, and PSIA, respectively.

However, the Quantum™ can be configured to return all
temperature and pressure data in the prescribed Panel
Units. This change can be made by setting address 49021
to 1 (Panel Units). The Panel Units can be accessed and
altered in the human interface (HMI) by selecting MENU

→

SETPOINTS

→

PANEL.

A mode such as Defrost mode is sent as an integer value
that represents 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
represent 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
modifiable. Read Only is used to help identify what data is
not modifiable. 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.