Triconex V/9 line monitoring

[20052000]

Dear experts,

Want to use line monitoring at an analogue input card at the Triconex V/9 system.
What kind of resistor network together with the field contact do I need to use to achieve this.

Thanks in advance.

Dennis

 

[Deadilus]

Dear 20052000,

Hopefully the following will help... As it happens, I am doing this on a v9 chassis (v10.3 MPs) for a project right now!

NOTE: I am assuming you are using a true switch in the field (i.e. short-circuit or open-circuit) - some F&G devices go low impedance to high impedance and this changes the calculations. We have some of these and it makes the calculations a little more complex, but the basic principle is still the same.

Whilst the exact resistor values can be varied, the attached spreadsheet shows that using a pair of 1k5 resistors (one across the switch terminals and the other on the input [or output] side) will give good results for a voltage range of 18-30Vdc, with a healthy current ranging from 6-10mA and an alarm current ranging from 12-20mA.

Adjusting the resistor values in the yellow fields will allow you to adjust your resistors and see what happens. Remember that (1) you should aim to always be within 4-20mA and (2) a larger gap between the high-end healthy and low-end alarm is helpful in preventing spurious alarms.