I am trying to integrate a Modbus RTU device (Emerson ROC809) into a HART communications network (digital HART FSK over 4-20mA loop). The ROC809 offers Modbus RTU so I need a system that will translate Modbus RTU into HART to connect to a Siemens S7-400 with PDM. The key is that the ROC809 needs to be a HART slave and not a HART master. Most Modbus to HART converters are set up as HART masters with the intent of converting outputs from HART slaves for the RTU.

I understand that PDM needs EDD files so that is not the issue. I am looking for a system that translates Modbus RTU into HART and does not act like a HART Master. I need the ROC809 to be a HART slave relative to the Siemens S7-400 with PDM.

Thanks in advance.
Steve

 

> I understand that PDM needs EDD files so that is not the issue. <

I suspect it is an issue. When I've used PDM to configure Siemens ultrasonic level devices, like a MultiRanger, I've created a project in PDM whose comm link is Modbus, not HART.

But, to my knowledge, that only works because I've gotten a driver (whatever its 3 letter acronym is, it's still a driver) from the Siemens web site which has been written to deal specifically with the device, the MultiRanger, and PDM's Teutonic personality.

Even if you find a HART slave to Modbus converter box, it isn't clear to me why PDM would establish communications with your device, because there's no specific driver for PDM to call up.

Unless, of course, PDM already has a Modbus driver for your device, in which case, it isn't clear why you would be seeking a HARTslave/Modbus converter.

Dan W