looking for RS485 hub

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Hiya,

I cant seem to google up what i want, so im wondering if anyone here
has any experience in rs485 networking, and knows of a suitable hub to
use.

The setup;

i have 8 banks of rs485 nodes.
each bank has upto 32 nodes.
Each node sends, does not receive.
banks are not inter-connected in any way.


I am looking for a hub which each 'bank' would connect to (much like
an 8port network hub). This hubs 'function' would be to send all
incoming data from the nodes of each bank, out a 9th port (9th port
being tcp network. 485. 232. whatever).

I dont want to send anything to the nodes.
All the hubs i have seen specify that they will send '1 to many', as
in the host says it once, and all will receive it. This is not what im
trying to do.
Will these hubs also go the other way, who knows, all the docs i have
seen dont specify this.


Okay, now to add a probably unrealistic wishlist to it;
-have the hub append a 'bank number' to each incoming serial packet of
XX bytes, before sending it out. (this way my nodes need only be
unique within a single bank)
-have the hub with some memory, and send out with a form of flow
control, so if the host PC goes down, when it comes back up, it will
collect the data for the past XXX minutes (depending on amount of
memory).

I can do without those functions, but they would be nice.

I have considered using an embedded board, with a bunch of comm inputs
and 485 converters, in a box and making it myself pretty simply.
but it MUST exist, i would have thaught it a fairly common device ?

Also, i will need a bunch of them, but sporadically. I dont want to
make 50 of them and have them sit around doing nothing for a year, but
i may well need 50 over a year. So its better for me if i can just buy
them as i want them.


Any ideas ?

Alex.