Siemens system to replace AB

Hi All,

I work for an OEM and all our machines go out with AB PLC´s, almost exclusively Compact Logix PLC´s but some Control and Micro logix controllers are used.

A client has requested one of our machines using siemens plc´s. We tried to persuade him to accept AB (even by charging a hell of a lot more for siemens) and they were willing to pay the premium for siemens.

So as I know nothing about siemens I was wondering if someone could help me out here with some information.

Our current machine uses the PLC set up below:
1769-L24ER-QB1BFC
1769-IQ32
1769-OB32
1 or 2 x Kinetix 300 Servo Drives (One could be a Kinetix 350, but because the L24 does not support motion we used a K300 instead, the other one uses the Current Index feature of the K300)

So basically 48 24V Digital Sink Inputs and 48 24V Digital Source Outputs. 2 x 0-10V DC Analogue Outputs (not necessary, we only use them because they are built into the L24) and we need 3 Thermocouple inputs (we use the Analogue inputs on the L24). We may or may not need a High Speed Counter module (I cannot remember if the Client wants to use an encoder or not) but lets assume that we do. One of the two servo drives needs to have a "Torque Index" feature (you send the servo drive to a specific position using position loop control, then without dropping the enable of the servo drive you switch to current or torque control and have the servo drive apply a specific torque or current for a period of time and then return to position control).

I read some stuff on the Siemens website and watched some videos on youtube but I´m still a bit lost on what Siemens is "equivalent" to what AB plc. Here is "roughly" what I think:
S200 ~~ Micrologix
S300 ~~ Compact Logix
S400 ~~ Control Logix

The S1200 and S1500 PLC´s I´m not really too sure of, and probably the client will ask us to use a 300 or 400 as that's what they have in their plant. Where I got lost was in trying to figure out how much memory I need, because the memory is very different to the AB memory. I cannot give specific details at the moment (don't have the software on this computer) on the number of counters/timers etc used, but I can tell you that we have a 0.5ms periodic task, a 5ms periodic task and a continuous task. If you need more info I can try and get it, just let me know what you need.

On the servo drive front I am completely completely lost! All help here would be appreciated!

So what I have so far really is a page with AB written on one side and Siemens written on the other and various bad words written about the Salesman and his mother All help would be gratefully appreciated.

Oh and just to add I will be doing some siemens training before I actually program this stuff don't worry, otherwise programming this would be very much like

Thanks all!
Ian

Edit to add:
We also use PID to control the Temperature output, so that will be needed. On the servo drives we do not use any sort of cam or other complex movements. Just absolute and incremental movements and one current/torque index. Ian

Your assessment is pretty close. I would steer away from the S7-200 were it my project, that is going to be a "legacy" product soon. The S7-1200 is the heir apparent. The S7-1500 is too new for me, I left Siemens a few years ago. But it looks as though that is intended to be the heir apparent for the S7-300, although the instruction execution time is a LOT slower and the memory capacity is a lot higher, so I have a hard time thinking about how that may play out in the grand scheme of things, seems like an odd mix of changes. However, the way Siemens organizes executable commands tends to make any direct comparisons to other manufacturers almost impossible just by looking at numbers, so the same might be happening now internally between the old and new versions. it's hard to tell with Siemens.

So I would rank them this way:

MicroLogix family = S7-1200
CompactLogix family = S7-300 with some crossover to S7-1500
ControlLogix family = S7-400

As to servos, that was a disaster for us at Siemens, but mostly because nobody in our local office was proficient in Siemens servo drives and there was very little support for them near to us and no commitment from management to change that. So if a project included any motion control, we tended to lose right out of the starting gate.

By the way, good luck! When I worked for Siemens, one of my biggest challenges in getting any A-B customers to switch was in the completely different thought process it takes to program in Step 7 compared to RS5000. Not impossible, just very different, and many people had a hard time adjusting. I hope you put enough money into it...

You sound like a high schooler who's girlfriend broke up with him

For the OP
Since this is a spec'd Siemens project and your standard is AB
Have your considered hiring an integrator to do the programming?

Can you tell use more about the machine ?

PLC said:

Since this is a spec'd Siemens project and your standard is AB
Have your considered hiring an integrator to do the programming?

Click to expand...

We are considering it, but we are also thinking about it as a possible investment in our programming department that way if another project is ordered with Siemens we would be able to do it in house. We will have testing time the biggest issue for us will probably be the servos. We'll have to see how it goes!

How many axis?
Do you need regenerative ? Size?

At the point in a project where you find yourself now I recommend getting a local distributor involved. If he is smart he will realize that this is an opportunity for him to generate a lot of future revenue - if he does his job right he may get lots more projects once you've bitten the Siemens bullet.

Have a salesman come in, and insist he bring technical support with him - possibly one person for HMI and one person for PLCs. That gives you a chance to asses their skill levels. If they aren't up to it look for another supplier - I'd be surprised if a place the size of Sao Paulo doesn't have several.

Have them do the cross reference from AB. This not only helps get it right, it gives them buy-in on the project. Find out about training, and support for software and program conversion from AB. Again, this lets them brag about their skills and gives them a stake in your project. You definitely want some training - when my company did its first Siemens job we paid for a couple of days special training for just us. That eliminates the "this is how you plug it in" level instruction and lets the training be specific to your needs. That cost us a little money up front, but it was money well spent.

When it comes time for purchasing ancillary items like contactors and power supplies and such, have the salesman come in with tech support and let them guide you.

The rep/distributor gets paid to add value to the supply chain. Let them earn it!

I would also say that you must contact the local Siemens distributor and get them to assist you to make the hardware setup.
They can assist you to choose the right PLC and servodrive for the job. When they have helped you with hardware they will also know what training you need to solve the job.

I have used Siemens to specify equipment for special job and received good service.

I think you are framing the question in the wrong manner. At the end of the day you really don't care which Siemens platform is like a specific AB platform. What you care about is that the platform selected can do what you want it to do. This requires that you really know what you want to do.

I agree that you should bring a Siemens rep in to evaluate the project. However, the question of which Siemens platform will replace an AB platform isn't relevant and shouldn't come up. What should drive the discussion is what you need to accomplish and that is it. That is how the rep will be able to give you the best platform to meet your needs. Just make sure the rep can fully explain why that platform was selected versus another.

Keith