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Problems with Mach3 Modbus TCP
« on: February 22, 2014, 04:36:39 PM »
I thought I'd try to communicate to my Modbus via TCP out of Mach3 and found what should have been simple, didn't work at all.  I have two VFD's on a Modbus 485 network and am trying to talk to them through a Phoenix Contact FL COMM Server RS485 converter.  The problem could always be in the COMM server, but I wouldn't think so. I will be digging into the COMM servers manual later tonight to see if I can find anything unusual, but the setup for what I'm trying to do seems pretty simple.

When I go into Mach3, open the Serial TCP Plugin, I added one line to the plugin for my Modbus Slave, I put the IP address of the FL COMM Server at the top, click on the test button and open the test screen.  Here I made sure the slave address was OK, IP address for the COMM server was OK, keyed an address in on the slave side, and clicked open.  I immediately get a connection timeout message.  I can see the activity light on the FL COMM Server light up each time I click the open button in Mach3, but get the same message, Connection Timeout.  I slid the slider below the addresses to the right and I then get Ethernet Connection Not Open as a message.

On the FL COMM Server (converter) side in the configuration I have the same parameters that are on the RS485 side, 8-E-1.  The only thing different is the drives have no hardware flow control, and the comm server has automatic for flow control and it isn't changeable.

I can ping the FL COMM Server from the PC running Mach3, in fact I can open the configuration on the COMM Server from that PC, so I know the Ethernet connection is OK.  I can also talk to the drives via the Modbus Serial Plugin on the computer running Mach3.  I simply opened that plugin, unchecked the box to enable the communication.  Clicked OK, restarted Mach3 just in case, opened the TCP plugin and set it up as explained above.  

I'm confused as to why I'm getting an immediate timeout message and it won't open the Ethernet connection.  I didn't see any settable timeout settings.  My finger doesn't even come off the mouse button before I see the timeout message.

What is Mach 3 looking for when you hit the Open button on the test screen?  I'd almost expect that if you have a live Ethernet device connected with the IP address entered in the test screen, that it would open the connection, even without anything connected to the other side of the converter, maybe I'm wrong.

Could I have missed something on the configuration side in Mach3?  Something isn't making sense here.

TeaMan
Re: Problems with Mach3 Modbus TCP
« Reply #1 on: February 26, 2014, 01:11:17 PM »
I was able to solve this.  I was thinking that the FL COMM Server should be a modbus master, thinking that the computer would communicate to the COMM server via ethernet, and the comm server would then convert ethernet to modbus RS485 and thus send that to the modbus slaves, making it a master.  My thinking was wrong, the comm server is also a slave and the computer is the master.  Switching the comm server to a slave opened the comms up and allowed the computer to pass through the comm server to the modbus slaves.  Hopefull this can help someone in a similar situation.

TeaMan
Re: Problems with Mach3 Modbus TCP
« Reply #2 on: February 26, 2014, 07:28:32 PM »
Ithink it is great that you solved your problem and then took the time to post it.
Mike
We never have the time or money to do it right the first time, but we somehow manage to do it twice and then spend the money to get it right.