Johnson Controls Frick QUANTUM LX, Setup

Page: 51 / 140

QUANTUM™ LX COMPRESSOR CONTROL PANEL
COMMUNICATIONS SETUP
090.020-CS (APRIL 13)
Page 51
Since this is the only address we are interested in
writing to, send the following message:
Look at this message on a more basic level, to un-
derstand how the address that we are writing to is
arrived at. We want to send the value of 1000 (100.0)
to the Regulation Mode 1 Setpoint, Frick® Address
7150 (decimal).
The fi rst part of the message will be a Colon (:). This
represents a heads up alert that data is coming down
the line.
}
: 01 06 1B EE 03 E8 05 CRLF
Where:
Message Start:
Quantum™ ID #:
Write Function:
H. O. address (hex):
L. O. address (hex):
H. O. # of Data Value:
L. O. # of Data Value:
Error Correction Code:
Carriage Return - Line Feed:
Any time that a message is sent, all of the Quantum™
panels that are on the MODBUS® network will be-
come active, communications wise, once the Colon
appears. Next, all panels will look at the fi rst byte
following the Colon (:). If this byte equals the Panel
ID # of the particular Quantum™ being queried, it will
immediately fi nish reading the remainder of the mes-
sage. If the byte does not equal its ID #, the message
will be ignored.
: 01 06 1B EE 03 E8 05 CRLF
Where:
Message Start:
Quantum™ ID #:
Write Function:
H. O. address (hex):
L. O. address (hex):
H. O. # of Data Value:
L. O. # of Data Value:
Error Correction Code:
Carriage Return - Line Feed:
}
: 01 06 1B EE 03 E8 05 CRLF
Where:
Message Start:
Quantum™ ID #:
Write Function:
H. O. address (hex):
L. O. address (hex):
H. O. # of Data Value:
L. O. # of Data Value:
Error Correction Code:
Carriage Return - Line Feed:
In this particular example, we are strictly looking to
write a data value, so we will be performing a write
function (06):
7150 decimal equals 1BEE hex. Looking at our exam-
ple we see that we need a H.O. (High Order) address
and a L.O. (Low Order) address. Since all data sent
and received is in ASCII Hex Byte format, we need to
look at EE Hex as the Low Order portion of the ad-
dress. The High Order portion is 1B. Now our decimal
7150 is formatted as 1BEE Hex.
: 01 06 1B EE 03 E8 05 CRLF
Where:
Message Start:
Quantum™ ID #:
Write Function:
H. O. address (hex):
L. O. address (hex):
H. O. # of Data Value:
L. O. # of Data Value:
Error Correction Code:
Carriage Return - Line Feed:
}
The value that we wish to send is 100.0 (1000). The
Data Value part of the data packet is looking for a
High and a Low Order value. The number 1000 (dec)
must be converted to hexadecimal. This conversion
results in a value of 03E8 (hex). Separating 03E8 into
two bytes results in the Low Order Value of E8 (hex)
and the High Order Value of 03 (hex):
In order to ensure that the Quantum™ in question re-
ceives the data request accurately, we must append
an Error Check byte to the end of the message. This is
: 01 06 1B EE 03 E8 05 CRLF
Where:
Message Start:
Quantum™ ID #:
Write Function:
H. O. address (hex):
L. O. address (hex):
H. O. # of Data Value:
L. O. # of Data Value:
Error Correction Code:
Carriage Return - Line Feed:
}
: 01 06 1B EE 03 E8 05 CRLF
Where:
Message Start:
Quantum™ ID #:
Write Function:
H. O. address (hex):
L. O. address (hex):
H. O. # of Data Value:
L. O. # of Data Value:
Error Correction Code:
Carriage Return - Line Feed:
}