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Connecting DT80 to my laptop using RS485 to USB Converter

Hey folks

I am trying to connect DT80 to my computer and test whether I can read the registers for two thermocouple points that are connected via 485 connection.

On the serial port, I have 9-pin serial cable that I terminated to a RS485 to USB converter (https://www.amazon.ca/dp/B081NBCJRS). I use Pin no. 3 for A+, Pin no. 7 for B- and Pin no. 5 for G.

Then I plugged in to the USB to my laptop and I use Modbus Poll to try to read this.

I have configured the DT80 to communicate as RS485 via deX2 (Settings > Communication > Serial Port > Mode > RS485)

66844c93b81fc

I am getting the error message as per above (Read Error, Break condition).

Can anyone please tell me whether:

1) The RS485 pin assignment is correct (3 --> A, 7 --> B, 5 --> G)?

2) Any idea what the error message means?

3) What is the typical 485 connection you guys ever used?

Regards
Faiz

Hey folks I am trying to connect DT80 to my computer and test whether I can read the registers for two thermocouple points that are connected via 485 connection. On the serial port, I have 9-pin serial cable that I terminated to a RS485 to USB converter (https://www.amazon.ca/dp/B081NBCJRS). I use Pin no. 3 for A+, Pin no. 7 for B- and Pin no. 5 for G. Then I plugged in to the USB to my laptop and I use Modbus Poll to try to read this. I have configured the DT80 to communicate as RS485 via deX2 (Settings > Communication > Serial Port > Mode > RS485) ![66844c93b81fc](serve/attachment&path=66844c93b81fc) I am getting the error message as per above (Read Error, Break condition). Can anyone please tell me whether: 1) The RS485 pin assignment is correct (3 --> A, 7 --> B, 5 --> G)? 2) Any idea what the error message means? 3) What is the typical 485 connection you guys ever used? Regards Faiz

Hi faizmz,

You need to connect pin A+ to RTS Y, pin B- to Tx Z and pin G to D GND. RTS Y, Tx Z and D GND is the pins within the digital channels. These pins located in one of the 5-pins terminal.

The error message means you fail to get a response from the logger. The MODBUS Poll (MODBUS Master) is requesting data from dataTaker (MODBUS Slave).

Besides the wiring, you need to ensure to set the dataTaker to have a slave ID 1 (as we see from the MODBUS Poll setting) and assign the reading value to channel variable (CV). The CV will become part of the MODBUS register that you can call to retrieve the parameters. If you assign 1CV to store the reading value, you can use register address 0 in MODBUS Poll to retrieve the value.

Best regards,
dataTaker Expert

Hi faizmz, You need to connect pin A+ to RTS Y, pin B- to Tx Z and pin G to D GND. RTS Y, Tx Z and D GND is the pins within the digital channels. These pins located in one of the 5-pins terminal. The error message means you fail to get a response from the logger. The MODBUS Poll (MODBUS Master) is requesting data from dataTaker (MODBUS Slave). Besides the wiring, you need to ensure to set the dataTaker to have a slave ID 1 (as we see from the MODBUS Poll setting) and assign the reading value to channel variable (CV). The CV will become part of the MODBUS register that you can call to retrieve the parameters. If you assign 1CV to store the reading value, you can use register address 0 in MODBUS Poll to retrieve the value. Best regards, dataTaker Expert
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