I've been working with a Teco Genie II SG2-20VR-D PLC from FactoryMation.com (http://www.factorymation.com/s.nl/it.A/id.47/.f?category=1298)to interface with Mach3.  My issue is that ModBus seems a bit random in it's ability to work.  I'm also controlling a Teco 7300CV VFD, also from Teco and it works perfectly over Modbus.  I've tried three different USB to ModBus converters, all with the same basic results - no response, random responses, etc.  What I've tried so far is:

* 38,400-N-8-2/RTU (the default and unchangable rate)
* Different wire
* Isolating it from the VFD
* Seperate power supplies
* Different ModBus adapters
* Monitoring/Testing outside of Mach3 using SimplyModbus
* Resistors/Terminators as indicated in the manual

Since I have the VFD working so well over ModBus, I'm wondering if there is a anyone that is successfully using the Teco SG2 PLC working over ModBus?

* 38,400-N-8-2/RTU (the default and unchangable rate)
* Different wire
* Isolating it from the VFD
* Seperate power supplies
* Different ModBus adapters
* Monitoring/Testing outside of Mach3 using SimplyModbus
* Resistors/Terminators as indicated in the manual

Since I have the VFD working so well over ModBus, I'm wondering if there is a anyone that is successfully using the Teco SG2 PLC working over ModBus?

Hi,

By Different wire, I presume you mean you are using a differential RS485 bus for the 2 units. If so make sure you have the bus termination resistors in.

Also, you have provided very little information on your problem. We need more information.

Cheers,


Peter.