DSA additions
Thu, 2021-01-21 19:03 — VonLindsey
Clayton Lorenz of Spyder Controls Group is submitting DSA Additions
| Attachment | Size |
|---|---|
| RV-C DSA additions Jan 2021.docx | 13.99 KB |
We don't have any concern
We don't have any concern where these fall into the list so if new additions are appended that will be just fine.
DC Load is generic, but arguably does encompass a whole host of other devices that also have their own DSA and DGNs. For example, DC Dimmer is indeed a DC Load, but because it has unique characteristics it has been assigned a unique DSA and DGNs. A similar argument would indicate that a generic DC Half Bridge driver has sufficient unique characteristics that distingue it from generic DC Load, DC Dimmer, Window Shade, etc as to warrant a unique DSA. We view this as being a legitimate product category and assume that other developers in the future would also find value in this addition.
You misunderstand the purpose
You misunderstand the purpose of the DSA. The DSA is for the technician, so he can identify component functions and then zero in on where the problems are.
Suppose, for example, that a RVer brings his rig into a service center with a problem: specifically, his autogenstart system isn't working. There are at least a dozen reasons this might be the case - the genset may have an internal problem, the genset might not be communicating, the AGS device might be misconfigured, the battery monitor might be malfunctioning, etc.. The technician plugs in his service tool (or he taps into the RV-C network through a cloud connection, or he pairs his bluetooth device, . . . ) and he looks at the status of the various devices. The technician expects to see a meaningful list of devices - "Genset", "Genstart Controller", "Battery", etc.. He can then zoom in on each applicable device and check for errors.
"Half-bridge" simply does not fit into this list - it means nothing to the technician. A half-bridge is just a component, with no function of its own, and just knowing that there is a half-bridge on the network doesn't bring the technician any closer to understanding why the generator isn't starting. It only has meaning if it's attached to a device whose function is known - e.g. the genset - and thus it needs to be treated the same way we treat other comparable components - relays, fets, diodes, solenoids - that is, as SPNs.
The reason that we have both DC Dimmer and DC Load, even though they are fairly similar is not that they have different characteristics, but because DC Dimmer is well-defined product function that technicians will recognize. DC Load is a "necessary evil", a catch-all for oddball specialty devices, prototypes, and anything else that simply can't be described with an existing DSA and doesn't merit a submission. (For example, at SilverLeaf we implemented our prototype Seat using DC Motor and DC Load DSAs and DGNs. After successful prototyping, we submitted the Seat DSA/DGNs and updated our firmware to use the new protocol.)
To sum up, I invite you to take a quick look at the list of DSAs and all the SPNs. In the first list you'll find "Furnace", "Dimmer", "Thermostat", "Genset". In the other you'll find "FET", "Relay", "Solenoid". Which of these two lists does "Half-Bridge" seem to belong in?
Two items: 1) To be
Two items:
1) To be consistent with previous practice, the new DSA's should be appended after the existing DSAs, rather than prepended as 62 and 63. The original reasons for starting at 64 are no longer valid, but there is some value in being consistent about putting the new stuff on the bottom of the table. (Originally we sought to minimize conflicts with SAE J1939, which at that time had not defined any DSAs over about 20 or 30. Now the SAE table is into the 90's.)
2) A Breaker Panel is clearly a legitimate "device", but in what context would you have a DM-RV with DSA "Half-Bridge Driver"? The DM-RV should have a DSA such as "Awning" or "Generic DC Load", and the SPN/FMI would be "Half-Bridge Driver/Failure to Respond". Rather than a DSA, shouldn't this be a global SPN?