RS485 Converter to analog output

[MrRobo 0]

What is a good converter for a 5V DC flow sensor with a RS-485 Output(0-10 Volts) to convert to a analog output?It would be nice to have a converter that can step down to 5VDC for the input side.

I want to be able to read the 0-10 Volt DC output with my Festo Module that goes back to AB PLC

[BobLfoot 301]

Can you provide some discrete part numbers.

Your description is slightly confusing as 5V RS485 would be a TTL Communications Standard and 0-10V would be an analog signal already.

IF your FESTO Input is 0-5V and your Sensor is 0-10V a simple resistor based voltage divider will perform the conversion.

But as said at the top, Discrete Part Numbers would prove useful.

[MrRobo 0]

LQ_AN_SCC1-RS485-USB_ImplementationGuideSF06_EN_D2 (005)Sensor.pdf

 

 

It is around 3 volts into the flow sensor.Our Festo Bus is 24VDC and they offer a analog module however I need to change the RS485 that can read the flow in Milliamaps or 0-10VDC.I am just trying to see if fluid is flowing through a hose and need to get this data into the PLC via a Festo module that can take a analog input

[pcmccartney1 141]

You have us (meaning me) completely confused.

Your sensor is obviously RS485 capable.  But you keep talking about a Festo Bus, yet you post the topic in Allen-Bradley forum.

Does Festo have a RS485 module or capability?  No idea.

What is the Festo talking to, as in PLC platform?

The manual says the SCC1-RS485 would goto a PC with a RS485 PCI Board installed.  The other cable SCC1-USB conveters the signal to a USB format and again would have to goto a PC. 

Edited 5 Jun 2020 by pcmccartney1

[aawilliams 1]

I am not aware of a good way to directly output an analog signal from these sensors.  Sensirion's documents seem to indicate that this style sensor is not compatible with the SCC1-Analog cable that they offer for some of their other products.  The flow sensor itself has an I2C output.  If paired with the SCC1-RS485 cable you can get an RS485 serial output.  You would need the following to make the correct physical connections, while also providing +5VDC to the SCC1-RS485 cable on the non-data conductors.

Flow Sensor <-> 6 pin connector to 4 pin M8 adapter cable <-> SCC1-RS485 cable <-> Allen Bradley ASCII module, such as 1769-ASCII.

https://www.mouser.com/pdfDocs/Sensirion_Liquid_Flow_Meters_Operating_Guidelines_.pdf

 

On the software side it is possible but not trivial to poll the flow sensor using the SHDLC protocol referenced in your manual.  Encoding/decoding the command and response frames is sort of a pain in the PLC.  Maybe there is a better way.

[DanW 41]

The flow meter is clearly a lab unit  - it's construction, power source, line fittings, accompanying software and lack of industrial signal interface all peg it as a lab unit.  

Writing a conversion protcol driver for the device to get data into a PLC could take hundreds of hours, far more if you're inexperienced.

The flow meter is a thermal dispersion inferred mass flowmeter, similar in size flowmeters from vendors like Brooks, Aalborg, TSI Alnor, MKS.  It does have a 2KHz sampling rate, which you might need, but I doubt it.  You might consider buying a flowmeter that can interface to the process AND to the data collection or control needed.

@aawilliams  Welcome to the forum.  Your reply is cogent, readable and a very instructive reply for a first time (?) poster. Nice job. You must be a sojourner from some other controls forum to compose that high level a reply.