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How To Configure 1 NS(NT Link) On A PLC Link Network


Sometimes there is a desire for a complete automation system with PLCs, HMI and inverter's, but in a small format for example, using our small CP1 series PLC with a NS HMI and inverter's over Modbus. There is a problem though that the CP1 PLC series has the maximum of 2 communications slots and if there are multiple PLCs connected they can't communicate with the rest of the system. However by using PLC-Link protocol over the RS-232 or RS-422/485 it is possible to have the maximum of 9 units (1 Master, 8 Slave's) connected, and here is a quick guide on how to make it work.

Connecting multiple PLCs

Note: The CP1W-CIF11 is not insulated, so the total transmission distance for the whole transmission path is 50 m max. If the total transmission distance is greater than 50 m, use the RS-422A/485 port on the CP1W-CIF12 directly, or the insulated NT-AL001-E, and do not use the CP1W-CIF11. If the CP1W-CIF12 or NT-AL001-E is used, the total transmission distance for the whole transmission path is 500 m max.

Connecting HMI terminal

It is also possible to add one HMI to the network. In this example it will be 1 NS, 1 CP1H and 1 CP1L, connected to one network.


The NS has to be connected direct to the master (as show in the connection example below)

And if more PLCs have to be added (9 units (1 Master, 8 Slave's)):



In the Master PLC there is two different mode's that can be set for the I/O handling on the PLC-Link:

ALL (Complete link method): In this mode, every PLC has access to all other PLCs defined I/O addresses.


Master (Polling unit method): In this mode only the Master PLC has access to all other PLCs defined I/O addresses.

Settings in the Master:

  • Link Mode (as mentioned above) - how you want to control your I/O communication
  • How many units that you want on the network (NT/PC Link Max)
  • How many (I/O)words you want to distribute on the network (Link Words), max 10 words

Settings in the Slave:

  • Determines that it is a "PC Link (Slave)", (Mode).
  • Select a Unit number (PC Link Unit No.).


NOTE: The baud rate and format has to be 115200 and 7,2,E so we can use High Speed in the NS.



High Speed = 115200


NOTE: The NS screens Unit no can't be 0. It has to be 1 or higher.

Now you have made 2 PLCs and one NS screen communicating on one network.

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Created 2010-03-05
Modified 2010-07-27
Views 13096


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