Control.com - Nerds in Control

I have a project using the Temco Thermostats (TSTAT5) which are run on Modbus communication (daisy chain connection, total length about 100 meters)to communicate with the Opto 22 system (a SCADA system). The TSTAT5 is used to provide local HVAC control while at the same time communicate with the Opto 22 system. The Opto 22 system has the authority to access the TSTAT5 to modify setpoint etc. so as to provide central control and monitoring function. Currently, it appears no problem in the communication and can perform the good control and monitoring. But...

Recently, we extend the communication by inserting more TSTAT5 and certain I/O modules in between the Opto 22 and the existing TSTAT5. The total length of new added portion is appro. 80 meters with no T- Tapped connection. We happened to find the Opto 22 can only communicate with the new added TSTAT5 and I/O modules but not the existing one. Can anyone tell me what had happened on this new addition?

Thanks,
SK Wong

Hello SK- I suggest posing your question to Opto 22 Product Support at support@opto22.com, or call within the USA at 800-835-6786 (internationally at 951-695-3080). Our team of experienced support engineers are ready to help, at no charge to you (Opto 22 product support is always free).

Also, as noted in a recent OptoNews, Opto 22 has released a new version of the Modbus Integration Kit for PAC Project. From what I understand, there are significant improvements, and this update could prove helpful in tracking down any issues from an Opto perspective.

The new kit can be downloaded at no charge from:
http://www.opto22.com/site/downloads/drilldown.aspx?aid=3270< br>
Good luck with your project. And thank you for using Opto 22 products.

Regards,
-Benson