Has anyone tried adding I/O to the J1939 bus? I'd like to add several sensors (pyrometer, fuel pressure, etc) for display within VMSpc. I've found both integrated sensor/broadcasters and I/O controllers. Most appear to be targeting the OEM market. The Murphy XM500 module would cover my needs and at a reasonable cost: http://shopping.murcal.com/Catalog/J1939-CANbus-Input-Output-Modules/XM500-J1939-I-O-Module One thing that makes me nervous is they all seem to list OFF highway vehicles in their list of applications. Too hazardous to add controllers to the bus of an on highway vehicle? Any wisdom out there? Cheers, Jeff
--And I don't even have a coach. Hey Jeff--that's a pretty neat looking unit; specs are good. It seems, on the surface, to be a good match for picking up sensors that something else (other than the ECM) will/ can act on or display. The only gap is how to see the results. The VMSpc unit, for example, has a template for expected sensors. There's a pretty big range of these but its not infinite. If a fella added a shaft Wobulation Detector it would show on a device already listening/ poling for that can-bus message. However, the VMS units in general aren't listening for sensors not already programmed in. There may be an exception to the Glass Dash products (VMS645 ~ VMS757). Yet after talking with one of our programmers, its clear that an arbitrary sensor (such as our Wobulation Detector) wouldn't have a gauge style/ format pre-assigned so it may not even be seen. I'm going to talk with Martin about this to see what the limits are and if there's a list accessible which will show what can be incorporated to the PC unit. ...stand by... Art //
Oh, I ASSumed that EGT (SPN 173) and fuel delivery pressure (SPN 94) gauges would be available. Not the case? That I/O module is nice and reasonably priced, unfortunately the configuration kit is not, $545.
Hey Jeff, I've checked with the coders--the fellas ultimately responsible for creating a software bridge to bring additional sensors into the VMSpc (or other VMS unit.) They're pretty sure it would be a huge undertaking. The J1939 sensors (when detected) would have to be made part of a huge lookup table; one dynamically created/ added to. In the local parlance, this is termed "not trivial." That, in itself, is code for "buckle up, this may get rough." The VMSpc code is probably the most likely to undergo this change as it has the most memory space to work with. I would not count on *any* effort to bring this to the dash or other built-in units. Still, its possible...yet the time this would take is significant on a product line which is, at the end of the fiscal year, a non-profit item. As for the practical nature of EGT--oddly enough, this is not the usual request for DPs. Intake temp, Jake & retarder temps--these are the (more typical) limiters to engine life & performance. Very few (if any) have EGTs--this is more a gas engine concern. As for On or Off road application (per the ad)--one reason this may be a concern for on-road is the EPA and how *maybe* this could be somehow seen as a defeat device. Of course its the opposite, giving more info in fact. Maybe its also more an off-road sales...bigger pool of tinkerers and all that. I'm leaning towards the latter... Art //
Bummer, ok I'll give up on adding sensors to the bus. But I've got to take exception to your comment about EGT. I've never seen a semi tractor without an EGT gauge. EGT is mandatory if you are going to start playing with tuners, not that that is my intention. EGT is inversely proportional to fuel economy and high exhaust temps are turbo and even piston killers. Truckers usually idle until their EGT's are down before shutdown to protect turbo oil seals. I've read many forum posts on how coach owners have added EGT gauges to their rigs. The only reason coach builders can get away without them is that they all include automatic transmissions programmed to avoid the lugging at low RPM's that drives up EGT to dangerous levels. What in the wide-wide world of sports is "Jake temp"? Cheers, Jeff