SECTION 6. 9-PIN SERIAL INPUT/OUTPUT
6-9
FIGURE 6.7-1. Transmitting the ASCII Character 1
If the computer/terminal is configured as DCE
equipment (pin 2 is an input for RD), a null
modem cable is required. See the SC32A
manual for details.
6.7.3 COMMUNICATION PROTOCOL/TROUBLE
SHOOTING
The ASCII standard defines an alphabet
consisting of 128 different characters where
each character corresponds to a number, letter,
symbol, or control code.
An ASCII character is a binary digital code
composed of a combination of seven "bits", each
bit having a binary state of 1 (one) or 0 (zero).
For example, the binary equivalent for the ASCII
character "1" is 0110001 (decimal 49).
ASCII characters are transmitted one bit at a
time, starting with the 1st (least significant) bit.
During data transmission the marking condition
is used to denote the binary state 1, and the
spacing condition for the binary state 0. The
signal is considered marking when the voltage
is more negative than minus three volts with
respect to ground, and spacing when the
voltage is more positive than plus three volts.
Most computers use 8-bits (1 byte) for data
communications. The 8th bit is sometimes
used for a type of error checking called parity-
checking. Even parity binary characters have
an even number of 1's, odd-parity characters
have an odd number of 1's. When parity
checking is used, the 8th bit is set to either a 1
or a 0 to make the parity of the character
correct. The CR10 ignores the 8th bit of a
character that is receives, and transmits the 8th
bit as a binary 0. This method is generally
described as "no parity".
To separate ASCII characters a Start bit is sent
before the 1st bit, and a Stop bit is sent after
the 8th bit. The start bit is always a space, and
the stop bit is always a mark. Between
characters the signal is in the marking
condition.
Figure 6.7-1 shows how the ASCII character "1"
is transmitted. When transmitted by the CR10
using the SC32A RS232 interface spacing and
marking voltages are positive and negative, as
shown. Signal voltages at the CR10 I/O port
are 5V in the spacing condition, and 0V in the
marking condition.
BAUD RATE
BAUD RATE is the number of bits transmitted
per second. The CR10 can communicate at
300, 1200, 9600, and 76,800 baud. In the
Telecommunications State, the CR10 will set its
baud rate to match the baud rate of the
computer/terminal.
Typically the baud rate of the modem/computer/
terminal is set either with dip switches, or
programmed from the keyboard. The instrument's
instruction manual should explain how to set it.
DUPLEX
Full duplex means that two devices can
communicate in both directions simultaneously.
Half duplex means that the two devices must send
and receive alternately. Full duplex should always
be specified when communicating with Campbell
Scientific peripherals and modems. However,
communication between some Campbell Scientific
modems (such as the RF95 RF modem) is carried
out in a half duplex fashion. This can affect the
way commands should be sent to and received
from such a modem, especially when implemented
by computer software.
Содержание CR10 PROM
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Страница 9: ...CR10 TABLE OF CONTENTS v LIST OF TABLES LT 1 LIST OF FIGURES LF 1 INDEX I 1 ...
Страница 10: ...CR10 TABLE OF CONTENTS vi This is a blank page ...
Страница 14: ...CR10 OVERVIEW OV 2 ...
Страница 15: ...CR10 OVERVIEW OV 3 FIGURE OV1 1 1 CR10 and Wiring Panel ...
Страница 16: ...CR10 OVERVIEW OV 4 FIGURE OV1 1 2 CR10 Wiring Panel Instruction Access ...
Страница 17: ...CR10 OVERVIEW OV 5 ...
Страница 34: ...CR10 OVERVIEW OV 22 ...
Страница 35: ...CR10 OVERVIEW OV 23 FIGURE OV6 1 1 Data Retrieval Hardware Options ...
Страница 36: ...CR10 OVERVIEW OV 24 OV7 SPECIFICATIONS ...
Страница 37: ...CR10 OVERVIEW OV 25 ...
Страница 38: ...CR10 OVERVIEW OV 26 ...
Страница 51: ...SECTION 1 FUNCTIONAL MODES 1 13 This is a blank page ...
Страница 53: ...2 2 ...
Страница 62: ...SECTION 3 INSTRUCTION SET BASICS 3 6 ...
Страница 63: ...SECTION 3 INSTRUCTION SET BASICS 3 7 ...
Страница 68: ...SECTION 3 INSTRUCTION SET BASICS 3 12 This is a blank page ...
Страница 74: ...SECTION 4 EXTERNAL STORAGE PERIPHERALS 4 6 ...
Страница 79: ...SECTION 4 EXTERNAL STORAGE PERIPHERALS 4 11 10 0X X is current address enter address to change to 1 8 ...
Страница 88: ...6 5 FIGURE 6 6 1 Addressing Sequence for the RF Modem ...
Страница 110: ...SECTION 7 MEASUREMENT PROGRAMMING EXAMPLES 7 17 FIGURE 7 16 2 Well Monitoring Example ...
Страница 132: ...SECTION 8 PROCESSING AND PROGRAM CONTROL EXAMPLES 8 13 This is a blank page ...
Страница 197: ...SECTION 13 CR10 MEASUREMENTS 13 18 FIGURE 13 5 1 Circuits Used with Instructions 4 9 ...
Страница 203: ...SECTION 13 CR10 MEASUREMENTS 13 24 This is a blank page ...
Страница 215: ...SECTION 14 INSTALLATION AND MAINTENANCE 14 12 This is a blank page ...
Страница 218: ...APPENDIX A GLOSSARY A 3 and computers in a terminal mode fall in this category ...
Страница 220: ...APPENDIX A GLOSSARY A 5 This is a blank page ...
Страница 228: ...APPENDIX C BINARY TELECOMMUNICATIONS C 6 This is a blank page ...
Страница 230: ...This is a blank page ...
Страница 232: ...This is a blank page ...
Страница 234: ...APPENDIX G CHANGING RAM OR PROM CHIPS G 2 FIGURE G 1 Disassembling CR10 ...
Страница 235: ...APPENDIX G CHANGING RAM OR PROM CHIPS G 3 FIGURE G 2 Jumper Settings for Different RAM Configurations in Early CR10s ...
Страница 236: ...APPENDIX G CHANGING RAM OR PROM CHIPS G 4 FIGURE G 3 Jumper Settings and Locations ...
Страница 237: ...APPENDIX G CHANGING RAM OR PROM CHIPS G 5 This is a blank page ...
Страница 241: ...LIST OF TABLES LT 4 This is a blank page ...
Страница 253: ...CR10 INDEX I 10 This is a blank page ...