RCV420: RCV420 for 4 to 20mA RS233 application

Hugo Liu

Part Number: RCV420
Other Parts Discussed in Thread: TRS3232E

Hi Sir,

Our customer SPEC want to Design RS232 type 4 to 20mA receiver & transmitter, Similar as below,
Do you have TI solution suggest for me? What's the TI solution Benefits?

over 5 years ago

0 Miguel Robertson over 5 years ago

TI__Guru 62910 points

Hi Hugo,

I don't think I fully understand the application. RS-232 is a digital communications interface, while 4-20 mA is typically used for analog data; this makes conversion between the two less straightforward. Did you want a "simple" conversion where a high logic level on the RS-232 interface maps to a 20 mA output and a low logic level maps to a 4 mA output (for example), or did you want something that could communicate a range of possible values via RS-232 (e.g., by transmitting a byte or more of information) and then convert that to a current proportional to the data value?

Max

0 Hugo Liu over 5 years ago in reply to Miguel Robertson

Genius 5095 points

Hi Sir,

Does TI both have?
or you can share document for me to discuss with customer

Hugo

0 Tim Green1 over 5 years ago in reply to Hugo Liu

TI__Expert 6275 points

Attached may help distinguish between the two. Ti does have 4-20mA transmitters (XTR) and even DAC +XTR but that does not look at what customer i looking for. CL1090A.pdf

0 Miguel Robertson over 5 years ago in reply to Tim Green1

TI__Guru 62910 points

Tim,

Thanks for providing this reference. Based on this document it looks like the converter detects/transmits ~20 mA to represent a "mark" and a ~0 mA to represent a "space." A device like TRS3232E could be used in place of U2 on the schematics shown on pages 13 and 14, then.

Is there an XTR device that could replace the transmit/receive circuitry on the current-loop side (opposite the isolation barrier) in these schematics?

Max

0 Hugo Liu over 5 years ago in reply to Miguel Robertson

Genius 5095 points

Hi Sir,

Thank you very much.

Hugo

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RCV420: RCV420 for 4 to 20mA RS233 application