TheWaterboy
Lifetime Supporting Member + Moderator
I need solid reliable comms and because of Terrain and RF congestion I have to communicate my telemetry over licensed VHF (220 MHZ) That of course means low bandwidth.
The PLC's currently selected for the remote location are Ethernet only L30's . No serial (DF1) comms are even available for these. That part might be OK in this case because as I understand it, in addition to having smaller limitations on lengths of MSG elements, DF1 type comms must use N Registers and the desire is to use a single UDT containing Dints, Reals, Bits and a few Strings. This UDT would contain all the info that field site has to offer. Nice and clean bundling back at the concentrator end.
DNP3 was briefly discussed but I haven't read up on DNP3 enough yet to even think about what it would mean to this discussion. I welcome input on that too.
So, if all the above is true that leaves Ethernet comms as the only option for a data chunk this size (about 1k words).
So I set up a test in the shop using a MSG to transfer 500 reals (reading from the L32 to an L30) using a CalAmp Viper pair I have available.
When hardwired the MSG takes 45 ms to complete but when run over the radio it takes from 2.8 to 11 seconds to do the same task.
Can someone confirm for me this seems like normal numbers?
If I had someone in my area I could believe in (ahem, Ken Roach... ) I would buy a few hours of time to consult, but everyone seems to have their own angle depending on what they rep. I can get a concise RF consultation and did that, but the PLC to Radio / protocol selection is a different beast to get straight answers for, and I know enough to know I'm wading into deep water.
I welcome comments or pointers to useful materials.
The PLC's currently selected for the remote location are Ethernet only L30's . No serial (DF1) comms are even available for these. That part might be OK in this case because as I understand it, in addition to having smaller limitations on lengths of MSG elements, DF1 type comms must use N Registers and the desire is to use a single UDT containing Dints, Reals, Bits and a few Strings. This UDT would contain all the info that field site has to offer. Nice and clean bundling back at the concentrator end.
DNP3 was briefly discussed but I haven't read up on DNP3 enough yet to even think about what it would mean to this discussion. I welcome input on that too.
So, if all the above is true that leaves Ethernet comms as the only option for a data chunk this size (about 1k words).
So I set up a test in the shop using a MSG to transfer 500 reals (reading from the L32 to an L30) using a CalAmp Viper pair I have available.
When hardwired the MSG takes 45 ms to complete but when run over the radio it takes from 2.8 to 11 seconds to do the same task.
Can someone confirm for me this seems like normal numbers?
If I had someone in my area I could believe in (ahem, Ken Roach... ) I would buy a few hours of time to consult, but everyone seems to have their own angle depending on what they rep. I can get a concise RF consultation and did that, but the PLC to Radio / protocol selection is a different beast to get straight answers for, and I know enough to know I'm wading into deep water.
I welcome comments or pointers to useful materials.