Kodiak Recirculating Chiller Technical Manual
Manual # 820-0109, Rev. Y, 07/08/10
- 45 -
Check Lytron’s website
www.Lytron.com
for the most current technical information.
HOST INTERFACE DATA LINK
Control Package 3 only
1.0 Host Interface Data Link
The chiller supports basic host control capability through the Chiller RS-232 port.
1.1 Port
Settings
The host port runs at 9600 baud, 8 data bits, 1 stop bit, and no parity.
1.2 Flow
Control
The chiller negates the Chiller RTS (output from Chiller) line whenever the Chiller is busy in a non-interruptible
process. The Chiller ignores the Host CTS line. No software (Xon/Xoff) flow control is provided. It is the
responsibility of the host to issue only a single command for which a response from the Chiller Control is
required until the response is received from the Chiller Control. Inter and intra message timeout is defined as 1
second. (Typical response times and character pacing will be baud rate limited.)
1.3 Encoding
All characters are to be ASCII characters. All messages from the host to the control and from the control to the
host will have 0x10 (ASCII Line Feed) as a start-of-message delimiter, and 0x0D (ASCII Carriage return) as an
end-of-message delimiter. Permitted message characters are in the range of 0x20 through 0x7F
(hexadecimal).
1.4 Numeric
Representation
Hexadecimal numbers, using ASCII characters ‘0’ – ‘9’ & ‘A’ – ‘F’, will represent all numeric values. When the
Chiller Control returns multiple variables or parameters they will be white space separated (using ASCII 0x20).
The host should recognize and use comma, tab and space as white space characters.
1.5 Units
All temperature values will be communicated in two byte hex values of
°
Cx100 (.01 C
°
). Resolution of
temperature values is .1 degree. All pressure values will be communicated in integer psi with no offset.
1.6 Commands
1.6.1 The following host Control messages are defined:
1.6.2 Read Chiller Status
This command (‘R’) will cause the Chiller Control to return a complete status string with the
following form:
^JR ControlFlags AlarmFlags PlantTemp SetTemp Pressure ^M
Where: ControlFlags Status in Bit encoded Byte (2 chars). Assignments are:
Bit 7:
(MSB); Machine on:
Lights the temperature display and pressure indicator
bar
Bit 6:
Expansion Relay2 on:
Not used by host program
Bit 5:
Expansion Relay1 on:
Not used by host program
Bit 4:
Heater on:
Not used by host program
Bit 3:
Autopilot:
Not used by host program
Bit 2:
Condenser Relay on:
Not used by host program
Bit 1:
Cool Valve On:
Light the Cool Status
Bit 0:
(LSB); Celsius Display on: Determines the display in Low resolution
