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Digital Thermometer & Thermostat
with RS-232 Interface
Model 232DTT
Document No. 232DTT1795
B&B Electronics Mfg. Co. Inc.
P.O. Box 1040 -- Ottawa, IL 61350
PH (815) 433-5100 -- FAX (815) 434-7094
Internet:
http://www.bb-elec.com
sales@bb-elec.com
techsupt@bb.elec.com
B&B Electronics -- April 1995
232DTT1795 Manual
Cover Page
B&B Electronics -- PO Box 1040 -- Ottawa, IL 61350
PH (815) 433-5100 -- FAX (815) 434-7094
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Table of Contents
Summary of Contents for B&B Electronics 232DTT
- Page 1 Digital Thermometer & Thermostat with RS-232 Interface Model 232DTT Document No. 232DTT1795 B&B Electronics Mfg. Co. Inc. P.O. Box 1040 -- Ottawa, IL 61350 PH (815) 433-5100 -- FAX (815) 434-7094 Internet: http://www.bb-elec.com sales@bb-elec.com techsupt@bb.elec.com B&B Electronics -- April 1995...
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Page 2: Table Of Contents
ONNECTIONS CHAPTER 2. 232DTT FUNCTIONS .......... 3 ..............3 IGITAL HERMOMETER ............3 ROGRAMMABLE HERMOSTAT CHAPTER 3. 232DTT DATA FORMAT ........5 CHAPTER 4. 232DTT COMMANDS .......... 7 ..............7 EMPERATURE ................7 TATUS ..................8 ..................8 .............. 8... -
Page 3: Chapter 1. General Information
±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 232DTT is guaranteed to operate from 0-70 °C. 232DTT1795 Manual Chapter 1 B&B Electronics -- PO Box 1040 -- Ottawa, IL 61350... -
Page 4: Rs-232 Connections
RS-232 Connections The 232DTT communicates using pins 2, 3, and 7 (TD, RD and GND). However, power is drawn from the handshake lines RTS (pin 4) and DTR (pin 20). These connections must be present to power the unit. -
Page 5: Chapter 2. 232Dtt Functions
Temperature command is received, the DTT immediately reports back the result of the last measurement completed. Programmable Thermostat The 232DTT also functions as a thermosta t. 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. - Page 6 +12VDC 12VDC RELAY RELAY CONTACT COIL DTT OUTPUT TCOM Figure 1. Relay Output Connection When connecting a mechanical relay coil, or any inductive load to the DTT outputs, a reverse bias diode must be connected across the load to protect the DTT output against large voltages caused by the inductive load.
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Page 7: Chapter 3. 232Dtt Data Format
Chapter 3. 232DTT Data Format The DTT uses 9-bit, two’s complement format to represent temperature data. The ninth bit is the sign bit. If this bit is a 0, the temperature is above 0° C. If the bit is 1, the temperature is less than 0°... - Page 8 6. To convert to Celsius, divide by two. 7. To convert to Fahrenheit, multiply the Celsius value by 9; divide the result by 5; then add 32. In the BASIC language, these steps look like this: ‘DTT data has been stored in CHAR1$ and CHAR2$ negative = ASC(CHAR1$) ‘ASCII val of sign char (1 or 0) reading = ASC(CHAR2$)
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Page 9: Chapter 4. 232Dtt Commands
The DTT commands can be issued from a program, or even typed in from a simple terminal program. Two files are included on the 232DTT disk to help learn the DTT commands. A sample program with source code written in QuickBASIC 4.5 demonstrates all DTT functions and a simple terminal program is also included. -
Page 10: Read High
Read High Command: !0RH Arguments: none Response: contents of TH register in 9 bit two’s complement format (shown in boldface) Dec. Example: !0RH<0><50> ASCII Example: !0RH<NUL>2 Description: The TH register contains decimal 0 (ASCII NUL) and decimal 50 (ASCII 2). This converts to a temperature of 25 ° C. When the current temperature is ≥... -
Page 11: Set Low Thermostat
!0SL 9 bit, 2’s comp. none *NOTE: After “programming” the 232DTT, there is approximately 10ms of down time when the unit will not respond. Do not attempt to communicate with the DTT for at least 10ms after programming the thermostat registers. -
Page 12: Chapter 5. Software
After the software is installed on your hard disk, the following files should be located in the 232DTT directory: 232DTT_W.EXE, VBRUN300.DLL, and MSCOMM.VBX. To set up the 232DTT under windows follow the following steps: 1. Run Windows. 2. Select the “FILE” menu under the Program Manager. -
Page 13: Appendix A. Using Simpterm
Appendix A. Using SimpTerm B&B Electronics shareware terminal program, SimpTerm, is included on the DTT floppy disk. SimpTerm is a powerful troubleshooting tool which will allow you to communicate through up to four serial ports at any address or interrupt. You will need to know the address and interrupt of the serial port that the DTT is connected To use SimpTerm to communicate with the DTT, follow the instructions to open the port connected to the DTT. -
Page 14: Appendix B. Decimal/Ascii Table
X ctrl Y ctrl Z ctrl [ ctrl \ < ctrl ] ctrl ^ > ctrl _ 232DTT 1795 Manual Appendix B B&B Electronics -- PO Box 1040 -- Ottawa, IL 61350 PH (815) 433-5100 -- FAX (815) 434-7094...