Documentation Number 485DTT1795 Manual
Cover Page
B&B Electronics -- PO Box 1040 -- Ottawa, IL 61350
PH (815) 433-5100 -- FAX (815) 433-5105
Digital Thermometer & Thermostat
with RS-485 Interface
Model 485DTT
Documentation Number 485DTT1795
This product
Designed and Manufactured
In Ottawa, Illinois
USA
of domestic and imported parts by
B&B Electronics Mfg. Co. Inc.
707 Dayton Road -- P.O. Box 1040 -- Ottawa, IL 61350
PH (815) 433-5100 -- FAX (815) 433-5105
Internet:
http://www.bb-elec.com
orders@bb-elec.com
support@bb.elec.com
B&B Electronics -- April 1995
Not Recommended for New Installations.
Please contact Technical Support for more information.
Documentation Number 485DTT1795 Manual
Table of Contents
i
B&B Electronics -- PO Box 1040 -- Ottawa, IL 61350
PH (815) 433-5100 -- FAX (815) 433-5105
Table of Contents
CHAPTER 1. GENERAL INFORMATION ..........................................1
I
NTRODUCTION
.............................................................................................1
F
EATURES
.....................................................................................................1
P
ACKING
L
IST
...............................................................................................1
S
PECIFICATIONS
............................................................................................2
CHAPTER 2. 485DTT FUNCTIONS......................................................3
D
IGITAL
T
HERMOMETER
...............................................................................3
P
ROGRAMMABLE
T
HERMOSTAT
....................................................................3
CHAPTER 3. 485DTT DATA FORMAT ...............................................5
CHAPTER 4. 485DTT COMMANDS.....................................................7
R
EAD
T
EMPERATURE
....................................................................................7
R
EAD
S
TATUS
...............................................................................................7
R
EAD
H
IGH
...................................................................................................8
R
EAD
L
OW
....................................................................................................8
C
LEAR
S
TATUS
R
EGISTER
.............................................................................8
S
ET
H
IGH
T
HERMOSTAT
................................................................................9
S
ET
L
OW
T
HERMOSTAT
................................................................................9
S
ET
485 A
DDRESS
........................................................................................9
S
ET
T
URN
A
ROUND
D
ELAY
........................................................................10
CHAPTER 5. CONNECTING THE 485DTT ......................................11
P
OWER
C
ONNECTIONS
................................................................................11
RS-485 L
INE
T
ERMINATION
........................................................................11
M
ULTIDROP
A
PPLICATIONS
.........................................................................11
CHAPTER 6. SOFTWARE ....................................................................13
I
NSTALLATION
............................................................................................13
W
INDOWS
S
ETUP
........................................................................................13
APPENDIX A. USING SIMPTERM.....................................................15
APPENDIX B. DECIMAL/ASCII TABLE...........................................17
Documentation Number 485DTT1795 Manual
Chapter 1
1
B&B Electronics -- PO Box 1040 -- Ottawa, IL 61350
PH (815) 433-5100 -- FAX (815) 433-5105
Chapter 1. General Information
Introduction
The 485DTT is a digital thermometer and thermostat which
operates through an RS-485 interface. Non-volatile registers hold
programmable high and low thermostat settings. Current
temperature is reported by polling the DTT, while thermostat
operations continue as long as the unit is powered. The RS-485
interface allows multiple units to communicate up to 4000 feet on a
single pair of wires.
Features
0.5
C accuracy and resolution
High, low and hysteresis type thermostat outputs
Thermostat thresholds programmable in non-volatile registers
Status Register latches if thermostat outputs have tripped
Programmable node address and turn around delay
Packing List
Examine the shipping carton and contents for physical
damage. The following items should be in the shipping carton:
1. 485DTT
unit
2. One 485DTT 3.5" disk
3. This instruction manual
If any of these items are damage or missing, contact B&B
Electronics immediately.
2
Chapter 1
Documentation Number 485DTT1795 Manual
B&B Electronics -- PO Box 1040 -- Ottawa, IL 61350
PH (815) 433-5100 -- FAX (815) 433-5105
Specifications
Communications:
Standard:
RS-485 two or four-wire
Baud Rate:
1200 to 9600 (automatic detection)
Format:
8 data bits, 1 stop bit, no parity
Connector:
DB-25S (female), RS-530 pinouts
Optical Isolation: If optical isolation is required, use B&B's
485HSPR high-speed optically isolated converter with this product.
Thermometer Error
0.5
C from 0 - 70
C
(
0.9
F from 32 - 158
F)
1
C from -40
C to 0
C and 70
C to 85
C *
(
1.8
F from -40
F to 32
F and 158
F to 185
F)
* The 485DTT is guaranteed to operate from 0-70
C
Thermometer Resolution
0.5
C (0.9
F)
Temperature Conversion Time
1
second
Open Collector Thermostat Outputs
Low (on) voltages:
1.2VDC @ 100 mA max
High (off) voltages:
40VDC max
Power Supply
External power: 12VDC @ 25mA
Documentation Number 485DTT1795 Manual
Chapter 2
3
B&B Electronics -- PO Box 1040 -- Ottawa, IL 61350
PH (815) 433-5100 -- FAX (815) 433-5105
Chapter 2. 485DTT Functions
Digital Thermometer
The 485DTT continuously measures temperature, with a
new measurement completed once per second. When a Read
Temperature command is received, the DTT immediately reports
back the result of the last measurement completed.
Programmable Thermostat
The 485DTT also functions as a thermostat. Two non-
volatile registers can be programmed. The high threshold register,
TH, is programmed using the !0SH command. The low threshold
register, TL, is programmed using the !0SL command. Chapter 4
describes all 485DTT commands. Thermostat operation is a
continuous background function. As long as the unit is powered, the
thermostat outputs will be serviced.
Three open collector outputs provide thermostatic controls.
These outputs are current sinking (low) when on, high impedance
(high) when off.
1. T
HIGH
- Turns on when the temperature equals or exceeds the
user programmed TH register
2. T
LOW
- Turns on when the temperature is equal to or less than
the user programmed TH register
3. T
COM
- Turns on when the temperature equals or exceeds the
TH register and turns off when the temperature is equal to or
less than the TL register. This output allows the user to program
any amount of hysteresis.
Remember, these are open collector outputs. They do not
source any current (similar to a contact closure to ground). For
example, to drive a relay with a 12VDC coil with the TCOM output,
connect as follows:
1. Connect +12Vdc to one side of the relay coil.
2. Connect the other side of the coil to the TCOM output.
3. Connect the ground of the 12V supply to the GND terminal
block.
PDF 
ZIP