Configuring the GRIB Decoders

As noted in Configuring the Data Monitors, the DMGRID, DMBIN and DMCOND data monitors control the GRIBDEC, GRBFILER and CONDUITFILER decoders, respectively. If activated, the data monitors perform the following actions with real-time NCEP GRIB messages.

The DMGRID data monitor decodes the GRIB1 messages then creates and stores them in McIDAS Grid files.
The DMBIN data monitor files the GRIB1 and GRIB2 messages into GRIB files of the same format and populates the MySQL/MariaDB database.
The DMCOND data monitor files the GRIB2 files from the CONDUIT LDM feed into a separate spool file. This optional procedure is useful for sites that receive their data via the LDM and helps ensure that data processing keeps up with the data during high volume periods.

You can activate the data monitors as needed and make their data available to your users in datasets defined in Configuring the Default ADDE Datasets. Keep in mind, however, that SSEC tests and supports real-time -XCD grid datasets only in GRIB format, and that McIDAS Grid files consume much more disk space than GRIB files. See Chapter 5, Decoding GRIB Messages, for more information.

The sections below contain instructions for configuring the data monitors.

DMGRID Data Monitor for McIDAS Grid Files

If you want to decode the GRIB1 messages into McIDAS Grid files, activate the DMGRID data monitor by running the command below from a McIDAS-X session running under the oper account.

Type: DECINFO SET DMGRID ACTIVE

DMBIN Data Monitor for GRIB1 and GRIB2 Files

If you want to file the GRIB1 and GRIB2 messages into GRIB files of the same format and populate the MySQL/MariaDB database with GRIB1/GRIB2 metadata, use the gribadmin and DECINFO commands below.

Create the MySQL/MariaDB database by running the command below from a Unix shell prompt. The command will prompt for a password. Enter the password for the MySQL/MariaDB root user, which was set by the person that installed MySQL/MariaDB.

Type: gribadmin makedb

If you have problems running this command, review the Configuration Sections section of the gribadmin script. It contains variables that change its behavior. In particular, the mysql_path and gcc_lib_path variables may need to be changed.

Activate the DMBIN data monitor by running the command below from a McIDAS-X session running under the oper account.

Type: DECINFO SET DMBIN ACTIVE

DMCOND Data Monitor for LDM CONDUIT Feed GRIB2 Files (Optional)

If you will be decoding CONDUIT products in a separate spool file, you must activate the data monitor. Otherwise, the CONDUIT data will be filed using the DMBIN data monitor. First, you must recreate the DECINFO.DAT file to add DMCOND to the list of valid data monitors.

Run the command below from the McIDAS-X Text and Command window to list the current active/inactive status of each of the data monitors. This information will be used in steps 5 and 6 below.

Type: DECINFO LIST

Run the command below from the Unix prompt to remove the existing DECINFO.DAT file.

Type: rm ~oper/mcidas/data/DECINFO.DAT

Run the command below from the McIDAS-X Text and Command window to recreate the DECINFO.DAT file.

Type: DECINFO

Run the command below from the McIDAS-X Text and Command window to activate the DMCOND data monitor.

Type: DECINFO SET DMCOND ACTIVE

Run the command below from the McIDAS-X Text and Command window to list the updated active/inactive status of each of the data monitors.

Type: DECINFO LIST

If the active/inactive status of any of the data monitors is different than it was in step 1 above, use the DECINFO command (DECINFO SET monitor action) to reset them to the proper status.

Creating a Separate Spool File for the CONDUIT Decoder (Optional)

This procedure is optional and is available only to sites that receive data via the LDM. The procedure increases throughput for GRIB messages by creating a separate spool file for the CONDUIT feed. If you are doing both the CONDUIT and NGRID LDM feeds in the same spool file, the tendency for dropped messages is possible.

Complete the steps below to implement the procedure.

Run the command below from the McIDAS-X Text and Command window to stop the DMCOND data monitor.

Type: DECINFO SET DMCOND INACTIVE
Run the command below from the McIDAS-X Text and Command window to add the new NCON circuit.

Type: CIRCUIT ADD NCON INGESTOR=INGEBIN CONFIG=CONDUIT.CFG SPOOL=CONDUIT.SPL "NOAAPORT NWSTG CONDUIT Binary Circuit
Run the command below from the McIDAS-X Text and Command window to define the full Unix path of the CONDUIT.SPL file.

Type: REDIRECT ADD CONDUIT.SPL "/data_directory_path

For example: REDIRECT ADD CONDUIT.SPL "/home/oper/xcd_data

Modify the LDM configuration so that it pipes CONDUIT data to another instance of the binary ingestor.
1. Open the file ~ldm/etc/pqact.conf for editing.
2. Create a separate entry in the Request Entries section for CONDUIT data and set it to pipe the data to the binary ingestor using the NCON circuit. First check if there is an entry that contains CONDUIT as well as other binary feeds such as HRS; if there is, remove CONDUIT from that entry. Then add a new entry like that in the box below, replacing its spaces with tabs (a requirement for the pqact.conf file).
  CONDUIT ^.* PIPE /home/oper/mcidas/bin/ingebin.k NCON
3. Save and close the file.
Run the command below from the Unix prompt to remove the old pointer file for the CONDUIT decoder.

Type: rm ~oper/mcidas/data/CONDUIT.PRO
Run the command below from the Unix prompt to stop and restart the LDM.

Type: ldmadmin restart
Run the command below from the McIDAS-X Text and Command window to activate the DMCOND data monitor.

Type: DECINFO SET DMCOND ACTIVE

You should notice very soon after starting the CONDUIT decoder that there is another entry in the ingestor section of the statdisp display. Three instances of the binary ingestor (INGEBIN) will exist if you are doing the optional NEXRAD decoder as well. The CONDUIT data should now be written to CONDUIT.SPL by the binary ingestor using the NCON circuit.

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