Help with NI cFP-RLY and cFP-DO modules 1

[KalevK]

We are building a new measuring and regulation system for our models. NI suggested to use Compact Field Point for our needs. Everything looks fine, but the relay modules (cFP-RLY 421 or 425) are too slow (421 has max 20 operations/s, i.e. 10 times on and 10 times off) for power regulation. Model surface temperature must be kept at 34 +/- 0.1 °C. In old system we use digital output components OPTO22 G4 ODC5, output 60 VDC 3A (20 kHz) that were controlled through triacs to supply power (switch closed % of time corresponding to required % of max power). There is also available digital output module cFP-DO-4xx series, that are comparable to OPTO22 specifications, however, I miss some information on their use. Does anyone know if there might be a triac function already built in there, or might it be possible to program such function in VI, or might it be that there are available fitting triac moduls, or should triacs be connected via special unit (system not "compact" any more)?

Regards,
Kalev

 

[xnuke]

What voltage are you trying to switch, and what duty cycle do you need?

I don't know of any cFP DO modules that can accept any higher than 30 Vdc except the relay modules you mentioned. The other DO modules have transistor outputs, not triacs, and most can deliver up to 2 A of current. If you need to deliver higher than 30 Vdc or more current than this, you'll need to use the cFP transistor-based DO modules to switch external devices that can handle the higher voltage (such as triacs or SSRs). Also, since it sounds that you're using pulse-width modulation to control the power delivered to the load, you may want to check out the cFP-PWM-520 (but you'll still need external interface devices to get higher than 30 Vdc or 1 A of current).

xnuke
"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
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[KalevK]

Thanks for tip. Duty cycle 0-100 % required. cFP-PWM-520 could fit with smaller models. Depending on model we use 8 to 60 V DC. We first settle with smaller models, so not over 30 V DC is needed. Max current to a zone with highest need is 1.3 A and to any small model zone below 0.5 A.