Table 12 Serial interface modes
Mode Description
STOP Probe outputs only when a command is issued. Any command can be used.
RUN Probe automatically outputs measurement messages on the serial line. Only
command S or the ESC key can be used to stop the output.
POLL Probe outputs only when a command is issued. Probes communicate one at a time
when the specific address is called on the serial line, which is useful when more than
one probe is connected to one serial bus. Any command can be used after the line
has been opened using the OPEN command.
See descriptions of the commands ADDR and OPEN.
MODBUS Measurement outputs must be read from the transmitter using the Modbus
protocol. For more information, see Modbus communication (page 29) and Modbus
reference (page 85).
VDIGI Special serial interface mode that is only used for interoperability with Vaisala
devices such as HMT120, HMT130, and HM40. This mode is set at Vaisala for probes
that are ordered for such use.
ANALOG No serial line, analog outputs active. For instructions on how to enter the serial line
when in analog mode, see Accessing serial line command interface from analog or
Modbus mode (page 36). Note that analog output channels are not available in the
digital-only HMP110. See Output options (page 12).
Example (check current mode):
smode
Serial mode : STOP ?
Example (change mode to POLL mode):
smode poll
Serial mode : POLL
In the RUN mode, the probe may send the measurement data message right as
you are typing the S command to stop the sending. Therefore, you may need to
repeat the S command. This must be noted especially when designing computer
programs to access the probe.
The digital-only HMP110 probe option cannot be set to analog mode.
Chapter 6 – Serial line communication
43
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