Modbus from Serial Port?

[lostcontrol 23]

Has anyone used this config before? I am assuming that the NS functions as a slave, so I would need to read/write from PLC as with any Modbus slave. We have an application that we are looking at, that only requires a CP1L, but also requires a VSD. I was going to write the speed to the VSD over modbus, so that we don't need to go to an analogue module. But they also want a HMI, so that this parameter can be adjusted.

[MPM 1]

Hi, Your apps is actually a NS, CP1L and 1 or several VSD ( V1000??) I think te CP1L manual describes the exact same application. easy modbus master option ( chapter 8) regards, MPM

[lostcontrol 23]

I am ok with the Easy-Modbus Master, but does the NS function as a slavo Or master? When I look at the config, my intuition tells me it is a master, whereas I would prefer it to be a slave.

[MPM 1]

Hi, Yes it is a master. you need 2 serial ports on your CP1L. one with CIF01 or CIF41 to connect to NS and one with CIF 11 (12) to connect with 485 ( modbus). regards, MPM

[lostcontrol 23]

Kinda defeats the purpose, no point using modbus with the NS to a CP1 when NT link is available. I was hoping to stick with the L range, and avoid the extra serial port, as the IO count for this one does not dictate going to the M range. The other option could be the NP series, these can be a slave by the look of it, and also 422/485 via terminals on-board. Edited 6 Oct 2009 by lostcontrol

[scottmurphy 1]

The NP will be your best option here. I have done something similar recently, and was a bit of work to begin with, but once proven, it is fine. The Modbus examples posted by PMCR are very easy to setup and get working for this, have a look and see how you get on.