SAMBA or not SAMBA

[JohnnyK]

Hi, my name is Johnny, and I am going to make the PLC programming on a project using a SAMBA controller.

 

I have been looking into the different videos and the forum, and right now, I have my doubt that SAMBA is the right choice. So instead of just buying more IO and stuff, and end up with an inconsistent setup, I would like your advice on the setup.

 

The controller are going to be placed in a lab machine and will go into production next year.
Meaning: “don’t use more money than necessary”, it’s not a onetime solution.

 

We thought that SAMBA would do the trick, and wanted to use the same controller in the next different models, to get more quantity on it, but if the total price goes to high (e.g. compared to V350) or it’s not possible to work with SAMBA we must change now.

 

Things that the PLC must be control:

·         1 output: RS-485 to a  Frequency inverter for a small one phase motor

·         1 output: Stepper motor

·         8 output: DC motor, (PWM or on/off in 0,1s interval) 24V 0,5A (max 3 active at the same time)

·         1 output: linear motor, PWM for precise force

·         3 output: LED

·         1 input (optional): hall sensor input to align stepper motor position (could be a hall switch(?))

·         1 input: strain gauge, slowly reacting close loop to linear motor (it could be a silicon strain gauge, 4-20ma)

·         2 input: switches

 

The only thing I can’t figure out is the stepper motor connection, do I have to add a external stepper controller or/and a stepper driver, or can it connect to the PLC directly?

 

If I stick to the SAMBA, I guess I need this list of hardware:

·         One SAMBA SM43-J-T20

·         One V100-17-RS4X, the RS-485 connection

·         One EX-RC1 adapter, connect to additional IO

·         One UID-0016T, additional IO

·         ????? stepper motor

 

Would this setup be better off using another controller?

 

Thank you, and have a great day.

 

@johnny

[Alexander]

The Samba is normally used for projects that only need the onboard I/O on the controller. Although it is possible to add a CANbus card and use an EX-RC1 and I/O expansions this may often be close to the cost of using a V350 which has the ability to use local I/O adapters and would not require the CANbus card and additional programming with the EX-RC1. The V350 also comes with a serial port that has the ability to communicate RS232/RS485 based upon jumper settings. An additional card would not need to be added for RS485 communications.

 

The Samba also has limited memory compared to the V350 and I would not recommend it if many screens need to be utilized.

 

The Samba T20 series do have the ability to use high speed outputs though it only has 8 transistor outputs. Only 6 can be used for PWM at 0.5Khz, 3 of those 6 can be used for PTO functions to control a stepper motor.

 

Program depending it may work but it may not be as cost effective as using a V350 to start. I would start by quoting both systems to see how the prices compare.

 

Also, do you know how many HMI screens do you will need?

[JohnnyK]

Thank you Alexander.

 

We are not going to have that many HMI screens, I would put it arround 10-12.

 

Would it actuarly be possible to have a CANbus and a RS485 installed in the SAMBA at the same time, or do they use the same connector?

 

We will compare the prices to see the difference.

 

Are the to setups like this?

 

SAMBA:

• One SAMBA SM43-J-T20
• One V100-17-RS4X, the RS-485 connection
• One EX-RC1 adapter, connect to additional IO
• One V100-17-CAN, CANbus module
• One UID-0016T, additional IO

 

V350:

• One V350

 

Or do we need more in the V350?

 

 

Thank you, and have a great day.

 

BR Johnny

[JohnnyK]

Had a little more time to look over the setup.

 

To have outputs enough, the V350 need to be a v350-J-T38 or a model that has less outputs combined with an IO card.

In both solutions, I need to have a LC1 for the load cell, will that connect to the SAMBA that has the additional IO mounted?

 

For the stepper motor, we only need the stepper driver, the PLC will do the input for that?

 

@johnny

[Walkerok]

Just my perspective,

 

SInce you have the need for so many transistor outputs and the load cell requirement I would use the following:

 

V350-J-T38

EX-A2X

IO-LC1

 

And since you have VFD to communicate with I would strongly suggest that you still add a V100-17-RS4X

 

You will want to set termination for both the VFD and the PLC as this really seems to help out with VFD noise.  Your com cable needs to be shielded and the drain wire needs to be as short as possible to a good ground source.  The com port on the V350 is not isolated and an isolated port will help.  We ship thousands of VFDs every year and have great experience with the trials and tribulations of comm errors in the presence of VFDs.

 

I know that this is not as low cost as the SAMBA but you will be much happier not having to dodge the limitations of the samba given all of the thing you are trying to do.

 

On the stepper, I never use them so I am unable to give you and answer to that question, but I am sure someone else will.

 

Good Luck

Keith

[JohnnyK]

Hi Keith

 

Thank you for your response.

 

I appreciate you input, especial on the VFD, I have had the same speculations on isolated com connections, and I think it a good idea to do so.

Will the V100-17-RS4X fit into the V350 house?

 

I need 12 digital outputs and 3 (?) for the stepper motor, that give a total of 15 outputs, why do I need the EX-A2X? (because it's isolated?)

 

Does anybody have a input for the stepper motor connection, the V350's digital PWM output will go to 500Hz, is that enough for a stepper motor?

 

So my V350 setup would be:

- V350-J-T38, PLC

- IO-LC1, Load cell

- V100-17-RS4X, isolated RS485

- (EX-A2X, IO expansion module - isolated)

 

And the SAMBA (can all this be connected to one SAMBA?):

- SAMBA SM43-J-T20

- IO-LC1, Load cell

- V100-17-RS4X, isolated RS485

- V100-17-CAN, CANbus module

- EX-RC1, Remote I/O Adapter

- UID-0016T, Uni-I/O Module - 16 transistor output

 

Br Johnny

[Joe Tauser]

Johnny,

 

You are way past what should be done in a SAMBA if you're rolling an LC1 into the mix.  Think of a SAMBA as a smart relay with a color touchscreen; any more than that is causing yourself way more trouble than it's worth unless there will be many, many copies of the system.

 

Rather than multiple posts on possible hardware lists, can you just post a drawing of what you're trying to do and let us suggest the I/O you'll need?

 

Joe T.

[Walkerok]

Hi Johnny,

 

The EX-A2X is dramatically lower cost that the EX-RC1 and you need at least the EX-A2X module to be able to use the IO-LC1 module.

 

Have Fun

Keith

[JohnnyK]

Hi

 

I spend some time on working on the programming on the SAMBA I have already.

I checked that the pumps, switches and light do run on the IO, making a service screen to make our mockup come alive.

And it all works, and the programming are just so nice to work with, thank you :-)

 

I made some drawings on the connection, please have a look.

 

 

Have a great day

 

@johnny

[Kikis]

Hi Johnny,

 

Regarding your question about stepper motors and 500Hz pwm...

 

Stepper motors are controlled via step & direction pulse.

You send pulses with 50% duty cycle to the driver and if the the direction signal is low motor rotates cw, while if the direction signal is high motor rotates ccw.

.

The speed of motor's rotation depends on the frequency of the output pulse and the resolution (pulse/revolution) of the stepper drive.

Most of the drivers are set by default to 400 pulses/rev (0.9 deg per pulse), but most of them have also the feature of micro-stepping.

The driver shown below can be adjusted by dip switches so that the resolution could be up to 50000 pulses/rev for more accuracy.

 

 

In order to calculate the pulse frequency needed, you need to know the desired rotation speed of the motor and the resolution of the drive.

[JohnnyK]

Thank you Kikis for your clarification.

Looking at your numbers the 500Hz will only drive the stepper a little more than one revolution/s and using micro steps even less, too slow.

 

By reading in the forum, I found that the SAMBA would not work on EX-A2X, only EX-RC1.

But how this is found in the Technical Library of Unitronics I am not sure, but it is good information when you have to select the additional IO :-)

 

@johnny

[Kikis]

Adding EX-RC1 would significantly increase the total cost of the control unit.

I think i'ts better idea to use a third-party modbus I/O module.

[JohnnyK]

Thank you Kikis.

I was not aware that any third-party modules could interface to the controller.

 

I have together with Unitronics support made these 3 setups, that I will look into cost.

 

Thank you all for your input :-)

 

 

@johnnyk