New to PLC wiring.. Help needed!

I am new to PLC wiring and desparately need some help. I need to wire a Siemens S7 200 PLC ( CPU 222) to 6 outputs. Two of the outputs go to a AC 110V powered solenoid valves and the four remaining outputs go to indicator lights on the panel. I have 4 inputs from switches on the panel.

The electrical specifications on the valve is
Power ratings 17.1 W
34 VA Holdings
64 VA Inrush

My question is.. Will the PLC be able to drive these outputs. I plan to use CPU 222 AC/DC/Relay and the specifications on the relay outputs say that the

Surge current (max.) is 7A contacts closed
Rated current per pt is 2.0A
Rated current per common is 10A
Lamp load max is 30 W DC and 200 W AC.

I have heard that PLCs with relay outputs have lesser life compared to the DC outputs. Do you think its better I use a CPU 222 DC/DC/DC and use 2 outputs to energise a relay and take that contacts for the 110 V valve?

Also, does anyone have any manual/write up that can give some information to begginers on load/power calculations?

Look below

I recommend you get the NEC handbook and NFPA 79, Electrical Standard for Industrial Machinery. These can be purchase from NFPA website:http://www.nfpa.org

IF near a local electrical supply house you may want to pickup an Ugly book, the actual name. Its an electrical guide with formulas, wiring info etc.

As for wiring just make sure the output can handle the load, which from the specifications there doesnt seem to be an issue. For the I/O wiring you shouldnt need anything larger than 14ga/1.6mm, I would probably use 16ga/1,25mm THHN or MTW for the I/O.

As for load power calculations the OHMS table is a starter, there may be info at this site of interest: http://www.patchn.com

Specifically: http://www.patchn.com/electron.htm

Hope this helps.

Here is a primer to help get started with S7-200:
http://www.ad.siemens.de/s7-200/html_76/primer.htm

Also the manual gives guidelines for wiring:
http://www4.ad.siemens.de/dnl/zI5NzI1AAAA_1109582/S7-200_e.pdf

Thanks for your reply rsdoran.

Now I know this is a stupid question but what does 14ga/1.6mm mean? Is that the spec for the wire? what does the 14 ga mean?

Also, isn't Watts and VA the same? Is there some phase angle involved in one? The valve specs says the watt rating and power consumption is 17.1 W, 34 VA holding and 64 VA inrush, what is the difference?

Thanks again for tolerating my stupidity..

In the US wires is sized by AWG (American Wire Gauge) or kcmil (Circular Mill). 14 gauge is a wires size that handles approximately 15 to 20 amps of current (this depends on type and situation). Wire comes in several types...ie THHN, MTW etc which specifies the insulation, temp, and capabilities. 1.6mm is the metric size for 14guage, I offered that for our International members.

VA, volt amperes, or vars, is the product of the rms voltage and amperage..ie the apparent power multiplied by the sine of the phase angle between the voltage and current.

Watts is the product of effective or actual power consumed by the load..ie volts x current

Therefore your solenoids at 17.1 watts divided by 120 volts = .1425 amps, which the relay output can easily handle.