in reply to: Re: Re: Multidropping hart devices. posted by John Emmett on 29 September 2008 at 18:02:17.
Yes, polling address 0 is conventionally kept for devices with analogue output enabled (and factory-fresh devices should be set this way).But HART rev 6 separates the parking of analogue current from the polling address setting, and also extends the polling address field to 6 bits, so you can address up to 64 devices. (But don't try polling addresses above 15 if the network might include rev 4 or 5 devices. If the devices are all pre-tagged, you can use command #11 to identify them.)
The original limit of 15 was a compromise with specified noise levels from each device. In practice, this may not be a problem and more than 15 devices in multidrop can work just fine.