Modicon M172 - AO1 as transistor output 24V DC

[Jacek_S]

I would like to ask for support regarding the configuration of an output in the Modicon TM172PDG18R controller. My goal is to use the AO1 analog output as a transistor output to control a relay in a continuous cycle: 15 seconds ON / 15 seconds OFF.

Here are my questions:

1. Is it technically correct to use output AO1 as a transistor output for this purpose?

2. How should the relay be properly connected to this output?

3. How should this output be configured in EcoStruxure Machine Expert – HVAC to achieve this cyclic behavior? (PARAMETERS)

I would greatly appreciate detailed instructions regarding both the wiring and the software configuration.

Thank you in advance for your assistance.

Best regards,
Jacek

[FedericoM]

Hi,

if you configure AO1 3=PWM Mode, the output becomes the collector output of a transistor.

The relay should be connected between 24Vout and AO1.

Frequency is too low to use the embedded function given PWM_Frequency_AO1_AO2 which define a fixed frequency while the output 0...1000 of the AO define the dutycycle %.

You have to implement the 15s period On and Off by code. Output 1000 when you want the relay On, output 0 when you want the relay off (polarity can be changed by parameter PWM_polarity_AO1_AO2) 

[M_Cervati]

Hi,

you can use AO1 in open collector configuration, connected like showed in the UG

It is possible to use 5V or 24V of this connector like pull-up of the load and you have to check the maxium current sink lower than 50mA.

An example how to configure the controller with ESME is in attachment.

Best regards

Marco Cervati

[Bastian_Schmitz]

Alternativ you could also use the Output as 0-10V output together with a SE Solid State Realy like these 

The relays act with an wide control voltage input. A few of my customers use this combination to control solnoid valves in pulse mode.