The number of I/O module that can be connected to IM151-3 PN HF

Hello,

I'm a begineer of SIEMENS PLC.

I want to know the number of I/O module that can be connected to IM151-3 PN HF.

As I saw the manual, it says :

1) It says "Thie must not exceed 10 A in total".
So, if rate current of I/O module is 0.5A (4DI 24VDC or 4DO 24VDC), is maximum module 5 EA ?
2 A (0.5 x 4 ) x 5 = 10 A ?

2) It says "63 Modules can be operated"

3) It says "This module supports a maximum of 256 I/O bytes."

I'm confused that by which factor it can be connected.
( Maximum modules )

Yes maximum is 63 modules or 2 meters.

The current consumption per modules is for the power module (PM).
Some outputs provide 24V power from the PM. And some inputs can supply 24V to an attached sensor. So you have to sum up the power consumption for these and if necessary split into several groups with each its own PM.

The 256 bytes is not a problem. There is enough for even a rack maxed out with 63 modules with analog I/O.

JesperMP said:

The 256 bytes is not a problem. There is enough for even a rack maxed out with 63 modules with analog I/O.

Click to expand...

To illustrate that last point:

As far as I know, that 256 bytes is 256 in AND 256 out. That means you would have to average more than 4 bytes of In or Out memory per module in the rack, to go over the limit. The only modules that I can think of off the top of my head that fit that requirement are the safety IO, although some of the technology modules may also fit the bill.

If you need a rack of 63 safety modules, god help you.

More question...

Thanks, JesperMP, mk42.

There are ome unclear questions to me.
What do you think of maximum current-carrying capacity(10A) for one PM module?

It says "Thie must not exceed 10 A in total".
So, if rate current of I/O module is 0.5A (4DI 24VDC or 4DO 24VDC), is maximum module 5 EA ?
2 A (0.5 x 4 ) x 5 = 10 A ? <<---------- Is it wrong ??


As for Input and Ourput module 24VDC supply,
do both modules supply 24VDC power to attached device ( relay or sensor etc.. ) ?
Are they different with just connection ? (it means 24VDC circuit route)
Input module : PLC(+) -> device -> PLC address point(-)
Output module : PLC address point(+) -> device -> PLC(-)
Do I understand correctly ?

Engineer Kim said:

Thanks, JesperMP, mk42.

There are ome unclear questions to me.
What do you think of maximum current-carrying capacity(10A) for one PM module?

It says "Thie must not exceed 10 A in total".
So, if rate current of I/O module is 0.5A (4DI 24VDC or 4DO 24VDC), is maximum module 5 EA ?
2 A (0.5 x 4 ) x 5 = 10 A ? <<---------- Is it wrong ??

Click to expand...

Input modules usually take a very small amount of current, (often only 100ma, or .1 A for the whole module), so check the technical specs for each module to see how much it needs.

For outputs, your math above is correct. If you do it that way, you will never run short.

However, one thing to consider is that even though the module is rated for .5A, teh actual device connected to it might only use .2A. Also, often you might have two outputs that could never be on at the same time, for example if you have one output for Forward and another output for Reverse. This means that you might be able to get away with 6 output modules instead of 5, or maybe more, depending on what you are trying to do.

Siemens has a tool that can help you build IO racks, to ensure you are following all the rules, like rack length, max number of modules, etc.

www.siemens.com/tia-selection-tool

Engineer Kim said:

As for Input and Ourput module 24VDC supply,
do both modules supply 24VDC power to attached device ( relay or sensor etc.. ) ?
Are they different with just connection ? (it means 24VDC circuit route)
Input module : PLC(+) -> device -> PLC address point(-)
Output module : PLC address point(+) -> device -> PLC(-)
Do I understand correctly ?

Click to expand...

Most ET200S input modules don't supply their own power, so it would be: 24V (+) -> device -> PLC input point

Most ET200S output modules don't need to return to the PLC, so it would be: PLC output point -> device -> 0V (-)

I think this is the same thing you had in your example, but I wasn't sure what you meant by PLC +/-.

However, some modules, like Safety IO, do require the same IO card to be both the source and the sink. Then it would be PLC Output -> device -> PLC Input, with the input and output actually being the same module, and in specific pairs.

Thanks, mk42

Your comment gave me big help.

I think that I need to study TIA tool.

Consider what kind of 'wiring style' you are using.

For ET200S, it is obvious to connect sensors and actuators directly to the ET200S terminal block, and thereby omit intermediary terminals. That typically means that the sensors and actuators needs to be supplied from the ET200S, as well as the return voltage (ground) has to be connected to the ET200S.
So if you connect sensors and actuators directly to ET200S, you have to account for the supply current to the sensors.

If on the other hand, you have intermediary terminals for sensors and actuators, or if the wiring is all internal in a panel, you typically do not get the supply voltage from the ET200S modules.

If you connect sensors and actuators directly to ET200S, you typically use 2 or 4 channel modules, due to the need for the supply and return terminals.
If you do not connect sensors and actuators directly to ET200S, you can use 8 channel modules.

Thanks, JesperMP