FAQ for DNP3
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FAQ for DNP3

Q: We've got a customer that using IOServer. They would like to know if it is possible to send a pulse control for a few seconds and then an off latch control using 1 command?
E.g They are currently sending a "1"  to 10.1.0.DO.3000,bool  which pulses the point on for 3 seconds. What they would like to do is pulse it on for 3 seconds and then set it back to "0".

A: According to the DNP3 standard, the device should have set that point back to 0 after the 3 seconds pulse command.

The attached pulsednp.io configuration shows how you can use the Write Delay parameter in OPC Gate Item to delay a write command. Note that the RTU will return an error if you send a write request to the same point before the previous pulse command have finished execution.

Writing a 1 to Modbus.10001 will pulse the output. Modbus.10001 will auto reset.

Q: We are using your DNP3 Slave. The timestamp that the master receives has a time offset that IOServer DNP3 Slave calculates in the section "Slave Station Options", option Time Offset. The question is how we can make that the time offset that IOServer calculates, zero. 
A: To stop the DNP3 slave from synchronising its time with the DNP3 Master. Set the DNP3 Slave.80.1.NeedTime Internal Indication to 0, before the DNP3 Master connects to the DNP3 Slave.

You can do this automatically as follows using the OPC Gateway
Source: 0
Destination: Device.80.1.NeedTime
Trigger: Device.80.1.NeedTime

Q: Please find attached the IOServer config and ios.log for Saturday, we had major comms issues on Saturday morning With NRSBU-Airport. Could you please have a look for any problems with NRSBU sites? 
A: Your communication problems are due to noise and errors in your communication channel. The chance of errors in a single transmission increases exponentially with the length of the frame, therefore you minimise the effect of errors by using as small a frame as you possible can. Class 0 polls cause the RTU to send large amount of mostly unnecessary data.

 You can reduce the effect of noise by:
1. Eliminating or reduce scheduled class 0 polls interval. 
2. Enable link layer confirm mode at the RTU. This cause each link layer frame to be acknowledged, minimising the effect of errors.

 
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Last updated: 06 December 2011