Hello all,
I have a question around auto/manual stations and if anyone can recommend any products that can perform this function.
A better description on my application:
Thanks,
Nick
I have a question around auto/manual stations and if anyone can recommend any products that can perform this function.
A better description on my application:
- We have an S7-300 PLC to is controlling a field device with a 4-20mA signal.
- 4-20mA feedback from the field device is connected to the S7-300 PLC.
- PID control loop is running in the PLC to control the field device.
- Under normal conditions (e.g. 99% of the time), the PLC will be controlling the field device, so everything is fine.
- However, we want to have the ability to still control the field device in open loop mode in case the PLC has failed.
- So effectively looking for a device that when selected to "Auto" will just repeat the 4-20mA signal from the PLC to the field device. When selected to "Manual" the operator can manually control the 4-20mA signal to the field device. If the 4-20mA signal from the PLC fails then the device will automatically switch to "Manual" mode.
Thanks,
Nick