Re: [MAT-devel] modbus use

[Andrey R. <an...@eq...>]

Maybe I explained myself not clearly enough because I don't see big
differences between what I wrote and what you proposed. Anyway,
here it goes.

>  Well, I have been thinking about this, and I am inclined to disagree
> with you.
>
>  The io addresses of the modbus module already presupose some kind of
> access control...
> e.g. (from modbus master module):
> map out slave1.out_word.123  Pt1
> map out slave1.out_word.124  Pt2
> map out slave1.out_word.125  Pt3
> map in  slave1.in_word.250   Pt4
> etc...
>
>  What I mean is that modbus already defines several distinct addressable
> areas; inputs are read-only, outputs are read-write, internal flags are
> read-write, etc... (I don't remember the details at the moment, I would
> have to check...). Anyway, I believe this is protection enough, without
> having to confuse users with another layer of in/out.

That's exactly what I meant. Let's see my configuration. I don't have a
working module yet but the config is along these lines.

[PLC]
point       L  "light"        Chaser at 0   4
point_alias    L1 "light 1"      L 0
point_alias    L2 "light 2"      L 1
point_alias    L3 "light 3"      L 2
point_alias    L4 "light 4"      L 3

module Chaser "../basic/chaser"
module plcshutdown "../../lib/util/plcshutdown"
module modbus_s "../../io/modbus/modbus_s_tcp"

[modbus_s]
# The "host" parameter defines the address to bind, which can
# be useful in multi-NIC configurations.
network tcp_net         tcp   host  cbe  port 5502  timeout .1 mode async

node digital_IO     tcp_net 34

map out digital_IO.out_bit.1 L1
map out digital_IO.out_bit.2 L2
map out digital_IO.out_bit.3 L3
map out digital_IO.out_bit.4 L4



>  What I propose is that the modbus slave be configured by:
> map out_word.123 Pt1
> map in_word.250 Pt2
> etc...

I think the map statement should include the modbus node (address)
because several slaves can be running at the same ip address.
BTW, what will the map look like for in/out operations? Something
like:

map out digital_IO.out_bit.1 L1
map in digital_IO.in_bit.1 L1


Take care,

Andrey