systemd-process-supervision.md

@@ -7,16 +7,25 @@ The AdvLigoRTS now includes [systemd](https://freedesktop.org/wiki/Software/syst
 For RCG models it is recommended to use the `rtcds` command line interface that comes with the `advligorts-rcg` package for building and installing real-time modules, and enabling/starting/stopping the module processes.
 Under the hood, the `rtcds` CLI is just issuing commands to systemd to manage things.  For general usage it's easier to just use `rtcds`.  The following describes what's going on under the hood.
 
-The RTS systemd units use systemd templates.  Template units are indicated by the `@` symbol in the unit name.  The top 
+The RTS systemd units use systemd templates.  Template units are indicated by the `@` symbol in the unit name.  Template units allow  arbitrary units to be constructed by name on the fly, by providing the template name after the `@` symbol (e.g. `rts@.target` would become: `rts@h1lsc.target`.
 
- * [`rts@.target`](https://git.ligo.org/cds/advligorts/-/blob/master/support/systemd/rts@.target): top level "target" template for an RTS model.  This is the primary unit one would interact with, and it makes sure the following dependent units are in the correct state.
+Here are the suite of template services for a single front end model:
+
+ * [`rts@.target`](https://git.ligo.org/cds/advligorts/-/blob/master/support/systemd/rts@.target): top level "target" template for an RTS model.  Manages the following: 
    * [`rts-module@.service`](https://git.ligo.org/cds/advligorts/-/blob/master/support/systemd/rts-module@.service): unit that actually loads/unloads the RTS kernel module
      * [`rts_module_ctrl`](https://git.ligo.org/cds/advligorts/-/blob/master/support/bin/rts_module_ctrl): wrapper script to load/unload kernel module
-   * [`rts-epics@.service`](https://git.ligo.org/cds/advligorts/-/blob/master/support/systemd/rts-epics@.service): EPICS IOC service
+   * [`rts-epics@.service`](https://git.ligo.org/cds/advligorts/-/blob/master/support/systemd/rts-epics@.service): EPICS IOC service, calls:
      * [`rts_epics_exec`](https://git.ligo.org/cds/advligorts/-/blob/master/support/bin/rts_epics_exec): wrapper script to exec EPICS IOC process
-   * [`rts-awgtpman@.service`](https://git.ligo.org/cds/advligorts/-/blob/master/support/systemd/rts-awgtpman@.service): awgtpman service
+   * [`rts-awgtpman@.service`](https://git.ligo.org/cds/advligorts/-/blob/master/support/systemd/rts-awgtpman@.service): awgtpman service, calls:
      * [`rts_awgtpman_exec`](https://git.ligo.org/cds/advligorts/-/blob/master/support/bin/rts_awgtpman_exec): wrapper script to exec awgtpman process
 
+The `rts@target` is the primary unit to interact with.  If you want to start the `h1lsc` model you would execute:
+```shell
+# sudo systemctl start rts@h1lsc.target
+```
+That would then start the `rts-module@h1lsc.service` to load the kernel module, the `rts-epics@h1lsc.service` to start the EPICS IOC process, and the `rts-awgtpman@h1lsc.service` to start the awgtpman process.
+
+
 ## DAQD
 
 The DAQD components are managed directly with systemd via `systemctl`.  Here are the various available services.