Campbell Scientific CR1000 Measurement and Control System - Manual (Page 350)

Section 8. Operation
350
Digital Display Direct Connect CS I/O Serial Comms
external keyboard / display Direct Connect Serial Comms
8.4.2 Protocols
The CR1000 communicates with datalogger support software
(p. 77)
and other
Campbell Scientific dataloggers
(p. 563)
using the PakBus
(p. 461)
protocol (PakBus
Overview
(p. 351)
). Modbus, DNP3, and Web API are also supported (see Alternate
Telecommunications and Data Retrieval
(p. 364)
). CAN bus is also supported when
using the Campbell Scientific SDM-CAN communications module.
8.4.3 Initiating Telecommunications (Callback)
Telecommunications sessions are usually initiated by a PC. Once
telecommunication is established, the PC issues commands to send programs, set
clocks, collect data, etc. Because data retrieval is managed by the PC, several PCs
can have access to a CR1000 without disrupting the continuity of data. PakBus®
allows multiple PCs to communicate with the CR1000 simultaneously when
proper telecommunications networks are installed.
Typically, the PC initiates telecommunications with the CR1000 via datalogger
support software
(p. 569).
However, some applications require the CR1000 to call
back the PC (initiate telecommunications). This feature is called Callback.
Special features exclusive to LoggerNet
(p. 569)
enable the PC to receive calls from
the CR1000.
For example, if a fruit grower wants a frost alarm, the CR1000 can contact him by
calling a PC, sending an email, text message, or page, or calling him with
synthesized-voice over telephone. Callback has been utilized in applications
including Ethernet, land-line telephone, digital cellular, and direct connection.
Callback via telephone is well documented in CRBasic Editor Help (search term
"callback"). For more information on other available Callback features, manuals
for various telecommunications hardware may discuss Callback options. Contact
a Campbell Scientific applications engineer for the latest information in Callback
applications.
Caution When using the ComME communications port with non-
PakBus® protocols, incoming characters can be corrupted by concurrent
use of the CS I/O for SDC communication. PakBus® communication uses
a low level protocol of a pause / finish / ready sequence to stop incoming
data while SDC occurs.
Non-PakBus ® communication includes PPP protocol, ModBus, DNP3, and
generic, CRBasic-driven use of CS I/O.
Though usually unnoticed, a short burst of SDC communication occurs at
power-up and other times when the datalogger is reset, such as when
compiling a program or changing settings that require recompiling. This
SDC activity is the datalogger querying the SDC to see if the external
keyboard / display is available.
When DevConfig and PakBus Graph retrieve settings, the CR1000
queries the SDC to determine what SDC devices are connected. Results