Campbell Scientific CR1000KD CR1000 Measurement and Control System - Page 550

C.2.2 Power States

Page 550 highlights

Appendix C. Serial Port Pinouts as a connection to a computer DTE device. A standard DB9-to-DB9 cable can connect the computer DTE device to the CR1000 DCE device. The following table describes RS-232 pin function with standard DCE-naming notation. Note Pins 1, 4, 6, and 9 function differently than a standard DCE device. This is to accommodate a connection to a modem or other DCE device via a null modem. Table 124. CR1000 RS-232 Pin-Out PIN: pin number O: signal out of the CR1000 to a RS-232 device. I: signal into the CR1000 from a RS-232 device. X: signal has no connection (floating). PIN DCE Function Logger Function I/O Description 1 DCD DTR (tied to pin 6) O* Data terminal ready 2 TXD TXD O Asynchronous data transmit 3 RXD RXD I Asynchronous data receive 4 DTR N/A X* Not connected 5 GND GND GND Ground 6 DSR DTR O* Data terminal ready 7 CTS CTS I Clear to send 8 RTS RTS O Request to send 9 RI RI I* Ring *Different pin function compared to a standard DCE device. These pins will accommodate a connection to modem or other DCE devices via a null-modem cable. C.2.2 Power States The RS-232 port is powered under the following conditions: 1) when the setting RS232Power is set or 2) when the SerialOpen() for COMRS232 is used in the program. These conditions leave RS-232 on with no timeout. If SerialClose() is used after SerialOpen(), the port is powered down and left in a sleep mode waiting for characters to come in. Under normal operation, the port is powered down waiting for input. Upon receiving input there is a 40-second software timeout before shutting down. The 40-second timeout is generally circumvented when communicating with datalogger support software (p. 77) because it sends information as part of the protocol that lets the CR1000 know it can shut down the port. When in sleep mode, hardware is configured to detect activity and wake up. Sleep mode has the penalty of losing the first character of the incoming data stream. PakBus® takes this into consideration in the "ring packets" that are preceded with extra sync bytes at the start of the packet. SerialOpen() leaves the interface powered-up, so no incoming bytes are lost. When the logger has data to send via RS-232, if the data are not a response to a received packet, such as sending a beacon, then it will power up the interface, send the data, and return to sleep mode with no 40-second timeout. 550

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Appendix C.
Serial Port Pinouts
550
as a connection to a computer DTE device. A standard DB9-to-DB9 cable can
connect the computer DTE device to the CR1000 DCE device. The following
table describes
RS-232
pin function with standard DCE-naming notation.
Note
Pins 1, 4, 6, and 9 function differently than a standard DCE device.
This is
to accommodate a connection to a modem or other DCE device via a null modem.
Table 124.
CR1000 RS-232 Pin-Out
PIN
: pin number
O
: signal out of the CR1000 to a RS-232 device.
I
: signal into the CR1000 from a RS-232 device.
X
: signal has no connection (floating).
PIN
DCE Function
Logger Function
I/O
Description
1
DCD
DTR (tied to pin 6)
O*
Data terminal ready
2
TXD
TXD
O
Asynchronous data
transmit
3
RXD
RXD
I
Asynchronous data
receive
4
DTR
N/A
X*
Not connected
5
GND
GND
GND
Ground
6
DSR
DTR
O*
Data terminal ready
7
CTS
CTS
I
Clear to send
8
RTS
RTS
O
Request to send
9
RI
RI
I*
Ring
*Different pin function compared to a standard DCE device. These pins will accommodate a
connection to modem or other DCE devices via a null-modem cable.
C.2.2 Power States
The
RS-232
port is powered under the following conditions: 1) when the setting
RS232Power
is set or 2) when the
SerialOpen()
for
COMRS232
is used in the
program. These conditions leave
RS-232
on with no timeout. If
SerialClose()
is
used after
SerialOpen(),
the port is powered down and left in a sleep mode
waiting for characters to come in.
Under normal operation, the port is powered down waiting for input. Upon
receiving input there is a 40-second software timeout before shutting down. The
40-second timeout is generally circumvented when communicating with
datalogger support software
(p. 77)
because it sends information as part of the
protocol that lets the CR1000 know it can shut down the port.
When in sleep mode, hardware is configured to detect activity and wake up. Sleep
mode has the penalty of losing the first character of the incoming data stream.
PakBus® takes this into consideration in the "ring packets" that are preceded with
extra sync bytes at the start of the packet.
SerialOpen()
leaves the interface
powered-up, so no incoming bytes are lost.
When the logger has data to send via
RS-232
, if the data are not a response to a
received packet, such as sending a beacon, then it will power up the interface,
send the data, and return to sleep mode with no 40-second timeout.