T
HERMO
C
UBE
PAO
C
HILLER
P
ART
#
52-400-2G-1-PAO
S
OLID
S
TATE
C
OOLING
S
YSTEMS
,
167
M
YERS
C
ORNERS
R
OAD
,
W
APPINGERS
F
ALLS
,
NY
12590
19
T
ELEPHONE
:
(845)
296-1300
F
AX
:
(845)
296-1303
WEB
V
ERSION
M9
RS-232 Communication Protocol
Table 2: Command and Data Bytes
Bit Position
Description
Bit =1
Bit = 0
Command
Byte
Bit 7 (MSB) Set Remote Control
remote control
local control
(chiller)
Bit 6
Remote On/Off
chiller On
chiller in standby
Bit 5
Communication
Direction
remote to chiller
(command from master)
chiller to remote
(status from chiller)
Bits 4 – 0
Parameters being communicated (see table 2)
Data Bytes
1 or 2 bytes depending on parameter (see tables 3 and 4)
Timing: ThermoCube PAO can accept a maximum of three commands per second
Table 3: Control Parameter
Bits 4 – 0
Parameter
No of Data Bytes
00001
Chiller set point 1 temperature
2
01001
Current fluid temperature at chiller coolant output
2
01000
Faults from chiller (fan, pump, RTD failure, etc.)
1
Table 4: Temperature Data Bytes (2 bytes)
The 2 data bytes for the temperature set point and transmission of the current temperature represent the
value of the temperature in 0.1°F increments. For example:
Temperature (examples)
High Byte
Low Byte
Hexadecimal
0.1
F
00000000
00000001
0001
1.0
F
00000000
00001010
000A
10.0
F
00000000
01100100
0064
20.0
F
00000000
11001000
00C8
30.0
F
00000001
00101100
012C
40.0
F
00000001
10010000
0190
50.0
F
00000001
11110100
01F4
60.0
F
00000010
01011000
0258
70.0
F
00000010
10111100
02BC
Table 5: Faults Data Byte (1 byte)
0 = OK, 1 = Fault
Bit Position
Fault Assigned
Hex value when fault is present
0
Tank Level Low
01
1
Fan Fail
02
2
Unassigned
N/A
3
Pump Fail
08
4
RTD open
10
5
RTD short
20
6
Unassigned
N/A
7
Unassigned
N/A
