I’m trying to test a HART hardware both in master side and slave side , I’m using A5191HRT HART modem IC from Onsemi, (because only its HART modem IC founded in shops our city), the biggest Disadvantages of this IC is circuit sample is low in internet, rather than other HART modem IC from TI , AD , MAXIM.
The main problem , I’m Involved in it, how HART voltage applied across sense resistance in master side can effect on current of current source(slave) and transmit HART data from master to slave side ?
In the real circuit I have tested , voltage across sense resistance cause current flow in itself circuit (get out from Op-Amp output pin and enter to GND master– red line ) (GND and VCC in master and slave is separate – two separate power supply)
While, what is expected to signal transmit from master to slave, I’m thinking that signal should pass from blue line.
In the experiment, I’m increasing the value of sense resistance to 10kohm and cause voltage applied sense resistance flow from red line