Communication between Speedac NXT weighing Controller and Honeywell Scada


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Earlier We had Speedac 7 Weighing controller used for Urea Packaging. It was communicating to Honeywell DCS over RS-485 serial protocol. The main purpose was DATA Logging in SERVER like total bag weight, Batch report etc.The connection was like

Speedac 7 -> RS 485 to RS-232 Converter -> Terminal Server (RCS 5016) -> Honeywell Exprion Server.

Now we upgrade Speedac 7 controller to Speedac NXT controller. Now we are not able to establish the communication.Please suggest if you have any option.

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Was the former device communicating properly right up until it was replaced or is the replacement attempting to fix a communications problem?

Both controllers have the same brand name, but is the replacement an exact replacement for the former? Changing model numbers can very well mean changed functionality.

Does the replacement use exactly the same communications protocol? By what authority? A salesman's verbal assurance or a studied review of the communication's documentation?

Did someone keep a record of which wire went where on the 485 side? Or are taking the 50% chance that th (+) is on the (+) and the (-) on the (-) terminal? Does the 485 wiring on the Speedac side remain the same pinout?