Modbus Control Problem

yanbin

Recently I tried to control A havc system using Modbus protocol( AMX controller works as master, HVAC as a slave), I got a Modbus worksheet from the HVAC company (as attached), I have the analog write and analog read working no problem, but digital write did not work at all.
for query the current temperature at master bedroom (address 3001) , I used below command:
$01,$04,$00,$00,$00,$01,$31,$CA , it worked fine,
but the cooling or heating enable/disable never work, can some have such experience give me a help?
Thanks,

yanbin

HARMAN_rgelling

I am not familiar at all with Modbus but only respond because I notice the protocol uses binary data. If you send the escape character (27 or $1B) anywhere in your data stream the next two bytes following it may be what is presenting a problem. The serial ports look for an escape sequence of characters to do things like enable/disable RTS, send a break character, switch to 9-bit serial, etc. The latest device side firmware which I think is available as a hot fix has a new command "ESCSEQOFF" to disable this mode so it will always ignore escape sequences.

Not sure this is anything remotely close to your problem but just thought I'd mention it.

ajish.raju

Toshiba TCS-NET Modbus Integration with AMX , Toshiba TCB-IFMB640TLE

I have a site where the client wants to integrate with the Toshiba TCS-NET modbus via RS -485. Does anyone have a modbus module for this device.

Do i need to get a modbus interface gateway to AMX or can i control it directly.

papadouk

Ajish.Raju:
You do not need any special hardware to control the Toshiba TCS-NET. What you have to do is connect the TCS-NET
directly on the NI controller. The protocol used by this Toshiba interface is MODBUS RTU and there is allready a
module available from the Tech Center (AMX web site) that will do your work. It also supports automatic polling of
modbus points.
Be aware that you also, might, need to configure the NI serial port to 485 ENABLE. Also check for the latest firmware
of your NI master and issue a "ESCSEQOFF" command as rgelling suggested.

Yanbin:
Try these commands for the Master Bedroom area:
ENABLE="$01,$05,$03,$E8,$FF,$00,$0C,$4A"
DISABLE="$01,$05,$03,$E8,$00,$00,$4D,$BA"
or
ENABLE="$01,$05,$00,$00,$FF,$00,$8C,$3A"
DISABLE="$01,$05,$00,$00,$00,$00,$CD,$CA"

I am not sure which of the 2 groups above will work. In the .doc you attached in your post the address for
the Master Bedroom Temp Set is 4001 for write and 3001 for read. The command you posted though is for
reading Input Register with modbus address 30001 (in the .doc is referenced as 3001).
...hope these will work for you. If not, let me know