Author Topic: master slave T100MD  (Read 12423 times)

pprojas

  • Newbie
  • Posts: 3
  • I'm a llama!
    • View Profile
master slave T100MD
« on: May 08, 2009, 01:52:47 PM »
I am sending the commando within a function from the PLC N? 1 (T100MD0808) to the PLC N? 2 T100MD0808:
 A$=NETCMD$ (3, " @02RI00")
 and of answer I have in A$ @02RI0059* and per moments I have  @01RI005A*, not to that it must since first is answer of PLC 2 and the message @01RI005A* is as if it was an error or some indication of PLC 1 from where I am sending the commando.
Please I want to know which is the razon
One friend for you

support

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3174
    • View Profile
    • Internet Programmable PLCs
Re:master slave T100MD
« Reply #1 on: May 08, 2009, 02:03:18 PM »
Note that only one PLC can be master and the other as slave at any moment. So if you use PLC 1 as master, then send "@02RI00" using NETCMD$ will get a response "@02RI0059*". There is no reason to receive "@01RI005A*" unless one of the following is happening:

1) The slave PLC (no. 2) is sending command to master PLC (no. 1) and the command is being read by PLC No. 1 as a wrong response.

2) You are connecting the RS485 network to a PC which is monitoring the PLC No. 1 and therefore the host link command sent by the PC is received by PLC No. 1 to be the wrong response string.

So please, check your system setup to make sure that no one else is sending command to PLC No. 1 which is the master.
Email: support@triplc.com
Tel: 1-877-TRI-PLCS

pprojas

  • Newbie
  • Posts: 3
  • I'm a llama!
    • View Profile
Re:master slave T100MD
« Reply #2 on: May 08, 2009, 03:26:06 PM »
Excuse me when I have only I/O digital boards with one PLC like master in wireless comunication I dont have problems, this problem appears when I put a PLC like slave.
 When the comunication is across fisical serial cable I dont have error message
One friend for you

support

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3174
    • View Profile
    • Internet Programmable PLCs
Re:master slave T100MD
« Reply #3 on: May 08, 2009, 10:15:23 PM »
Do you mean when you connect using two wire RS485 cable there is no problem but connect wirelessly (presumably through some kind of radio modem??) you have a problem? That sounds like a problem with the choice of the radio modem. The radio modem must be able to handle the link transparently. If you have a problem, try to communicate at a lower baud rate by setting the serial port for both master and slave to the same baud rate e.g. 9600 or 4800 bps and see if it would improve.

However, the fact that you receive "@01" when you are expecting "@02" still sounds to me like someone is sending command "@01" since the FCS is computed correctly.
Email: support@triplc.com
Tel: 1-877-TRI-PLCS

pprojas

  • Newbie
  • Posts: 3
  • I'm a llama!
    • View Profile
Re:master slave T100MD
« Reply #4 on: May 11, 2009, 03:04:43 PM »
The implemented system has 5 "Datrax" radio modem.
When I put the main PLC only with I\O cards the communication across the wireless it is always ok (with pc for supervision) the speed it is 9600 bps ,but  when I put the PLC 2 like slave (without program and without PC for supervision) the error appears in few seconds
One friend for you

support

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3174
    • View Profile
    • Internet Programmable PLCs
Re:master slave T100MD
« Reply #5 on: May 11, 2009, 06:18:30 PM »
Are the Datrax radio modems connected to PLC1 and PLC2 via RS485? When you test it with PC is it connected via RS232 or RS485? It is still completely unclear to me what your configuration is. May be you can describe with better details or a drawing (uploaded to any webserver and put a link here) to show what you are doing.

Is PLC1 the only master and PLC2 the only slave at all time?
Email: support@triplc.com
Tel: 1-877-TRI-PLCS