Ceilometer CT25K
CT25K-U059en-2.1 User’s Guide
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4. OPERATION
4.1 Operation Modes
There are two operation modes, continuous i.e. normal and standby.
Commands OPER_MODE STANDBY and OPER_MODE CONTINUOUS
are used to switch between the modes. In NORMAL mode continuous
measurement and message transmission occurs according to chosen
parameters. In STANDBY mode the wearing parts are turned off and it can be
used e.g. during periods when measurement is not needed. It allows single-
cycle measurement by command START.
Figure 4-1 Operation Modes
4.2 Serial Lines. Open and Closed Port
Two serial lines are provided, termed "MAINTENANCE" (external connector
J4, Line/Port A at Processor Board) and "DATA" (external connector J3,
Line/Port B at Processor Board). Line B is intended to be used for
measurement data communication and can be operated through modem or
baseband. Line A is intended for on-site maintenance access, and is used only
baseband. However, functionally the operation of the lines is identical; the
same commands, operations and messages operate through any of the lines,
and the following description applies to both of them.
Factory default setting is 7 data bits, Even parity, 1 Stop bit, and for baseband
lines, 2400 baud. Baud rate is selectable in the user menu.
7-bit USASCII character format is used. Letter case UPPER/lower can both be
used; response will use the upper case.
Standard operation of the serial lines requires no handshake signals.
A communication port, i.e. serial line, has two internal states (Figure 4-2):
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