dmmb.adoc

dmmb(1) Manual Page

NAME

dmmb - reads observations from Modbus RTU/TCP device

SYNOPSIS

dmmb --help

dmmb --version

dmmb --config file [--name name] [--node id] [--sensor id] [--logger name] [--format name] [--output file] [--mqueue] [--debug] [--verbose]

DESCRIPTION

The dmmb program reads values from or writes values to Modbus RTU/TCP registers by sequentially processing the job list loaded from a configuration file. Each request of an observation must contain the Modbus register parameters in the request string. The value of the first response is set to the result of the read operation. Up to 8 requests to read and/or write values are permitted. Integers read from a register may be scaled using an optional scale denominator.

The following fields are supported in the command string:

access [read|write]

Read or write value of given type.

address n

Register address.

code hex

Optional Modbus function code in hexadecimal format. Set to 0x01 to read coil status and to 0x05 to write coil status.

order [abcd|badc|cdab|dcba]

Byte order of type float.

scale n

Optional integer scale denominator.

slave id

Slave id.

type [int16|int32|uint16|uint32|float]

Data type to read or write.

value n

Integer value to write.

For example, to read a 2-byte unsigned integer from holding register 40050 of slave device 1 with a scale factor of 1/10, the attribute request of a request must be set to:

access=read, slave=1, address=40050, type=uint16, scale=10

Or, to read a 4-byte floating-point value in ABCD byte order from register 40060:

access=read, slave=1, address=40060, type=float, order=abcd

Only integer values may be written to an input register, for instance:

access=write, slave=1, address=30010, type=uint16, value=1

The value is converted to uint16 automatically. The command string can be in lower or upper case. White spaces will be ignored.

Observations will be forwarded to the next receiver via POSIX message queue if any receiver is specified. The program can act as a sole data logger if output and format are set. If the output path is set to -, observations are printed to stdout, else to file.

A configuration file is required to configure the jobs to perform. Each observation must have a valid target id. The database must contain the specified node, sensor, and targets.

OPTIONS

--config, -c file

File path to the configuration file.

--debug, -D

Forward logs messages of level LL_DEBUG via IPC (if logger is set).

--format, -f [csv|jsonl]

Output format of observations if --output is set. Either CSV or JSON Lines.

--help, -h

Print available command-line arguments and quit.

--logger, -l name

Name of logger. If set, sends logs to dmlogger(1) process of given name.

--name, -n name

Name of program instance, configuration, and message queue (default is dmmb).

--mqueue, -Q

Create message queue to receive observations.

--node, -N id

Node id.

--output, -o file

Output file to append observations to (- for stdout).

--sensor, -S id

Sensor id.

--verbose, -V

Print log messages to stderr.

--version, -v

Print version information and quit.

EXIT STATUS

0

Success. Process terminated without errors.

1

Failure. Process failed.

ENVIRONMENT

DM_LOGGER

Name of logger instance to send logs to.

NO_COLOR

Disable ANSI colour output.

EXAMPLE

Read the jobs to perform from configuration file and execute them sequentially:

$ dmmb -n dmmb -c /usr/local/etc/dmpack/dmmb.conf -V

SEE ALSO

dmmbctl(1)