Original question:
Dear,
about ISO1432B can support RS-485 and RS-422 at the same time? or have co-lay schematic can share us?
and ISO1432B is could possible can support half/full duplex, to both.
schematic as below chart:
If any suggestion, Please advise me.
Thanks,
Best regards,
Lawrence.
Hi Lawrence,
RS-485 and RS-422 interface only defines the electrical characteristics of the interface and ISO1432B meets both these requirements. Hence the device can be used either on RS-422 or on RS-485 without any concerns. Please refer to the below document for more details related to the two interfaces.
Yes, ISO1432B can be configured to half-duplex mode by directly connecting A/B lines to Y/Z to form one pair of wires.
The schematic looks good but you might protection components on the RS-485/RS-422 bus based on the EMC requirements. Please refer to the below reference design (TIDA-00731) that implements various protection components on the RS-485 bus to meet various EMC requirements. You can choose one or more of these components based on your requirement. Thanks.
Regards,
Koteshwar Rao
Hi, Koteshwar Rao
your mean is ISO1432B can be configured to half-duplex mode by directly connecting A/B lines to Y/Z to form one pair of wires.
is look like below chart right?
If any, Please advise me.
Thanks,
Best regards,
Lawrence.
Hi Lawrence,
Y & Z lines are the output lines and they together form one differential output signal. Similarly, A & B together form a single differential input. Connecting Y to A and Z to B will make the output connected to the input sharing the same communication cable together. With this approach, Y/Z port will be able to transmit data onto the RS-485 communication bus and at the same time A/B input port will be able to read all the data that is available on the RS-485 communication port.
Please do refer to the below block diagram from ISO3086 datasheet, this diagram indicates how full-duplex device ISO3086 is converted to form a half-duplex device ISO3088. Let me know if you have any questions, thank you.
Regards,
Koteshwar Rao
Hi Lawrence,
For ISO1432B PCB guidelines, I would recommend you to look at ISO1412DWEVM and you can take it as a reference PCB layout. It does have a few extra test points and jumpers to make it easy for evaluation but I believe those things may not be required on an end product. You can choose to omit those for your application. Please find below the link to ISO1412DWEVM.
Alternatively, you can also look at a reference design (TIDA-00731) for device SN65HVD82 (non-isolated RS-485 transceiver) that implements various protection components on RS-485 bus along with termination. Based on your requirement, you can choose what components you would need and refer this design for your PCB layout. You can find the link to this reference design below. Thanks.
Regards,
Koteshwar Rao
