Connecting Multiple Smart Serial Devices to a 7i76e

  So I have been contemplating using a 7i73 and a 7i71 connected to a 7i76e's smart serial line. However I have never done
it , and so far my searches have come up with little. As I understand it they work on the RS-422 protocol . If I understand that
correctly you have to run it kind of daisy chained. Meaning the cable probably runs to the 7i73 then from the 7i73 to the 7i71
then you have to set the device in the middle (7i73) to un-terminated (W10 W11 down) and the 7i71 to terminated
(W10, W11 up). Correct?
 

Nope each smart serial device requires it’s own smart serial channel.
So for 2 smart serial devices you need 2 channels.

The 7i74 plugs into a Mesa db25 connector but you’ll need firmware to suit store.mesanet.com/index.php?route=produc...83_87&product_id=117

Each SSerial device needs its own channel (they are RS-422 full duplex devices, not RS-485
half duplex) So you would need a 7I74, 7I85 (or just a SP491 chip wired to and expansion port)
to have more than the one built-in SSerial port on the 7I76E.

The reason we chose RS-422 is that:

1. All communications are done in parallel (so speed is the same regardless of the number of devices)
2. No marginal RS-485 termination issues (Async RS-485 devices need kludgy bias resistors to define the state
of the un-driven bus so suffer from lowered noise immunity compared to always driven full duplex RS-422)

Glad I asked.
So it's a point to point system like RS-232 but better. Got it.

JT wrote:

I might add you can flash the 7i76E with the correct firmware with my Mesa Configuration Tool.

JT
 

Thanks JT