working with S7-300 analog module

Hello guys,
I have a problem with S7-300 analog input module 8x12bit. I have configured module to expect 2 wire current (4-20 mA) by turning on D on module. Now I think that card is expecting current from 4 to 20 mA. I have conected calibrator (device that simulate current source) to the first channel but nothing happens. I suspect that card is maybe design to use it's on voltage supply to produce (with some transmitter) current 4-20mA.
Is there any way to make that card work with calibrator?

Thanks

What card are you using?


Did you turn the hardware-key on the module (if it has a hardware-key)?

Did you download the HW-configuration?

This is something you need to understand about Siemens naming for these signal types. When Siemens talk about 2-wire or 4-wire they are describing the type of transmitter to be connected and how many terminals it has.

If both the power to energise the transmitter and the measured signal level are to be transmitted through the same wires, then Siemens regards this as a 2-wire transmitter and obviously the analog module should be wired to provide the power to the loop.

If the transmitter has 4 terminals, 2 for the pwoer and 2 for the signal, then that is a 4-wire transmitter and the transmitter is energised by some external source, not the module.

Your calibrator presumably has its own power source (batteries?) and you do not expect the module to power it, so you should configure and wire the card for a 4-wire transmitter.

Regards

Ken

Ok, thanks for replies.
If I understood good I need to configure module as 4 wire current (I think hardware switch on the left side of module must be set to C). So then I assume it must work?

I've configured module's channels for 4-wire transducer and it works. Is it definitely that when module channel is configured for 2-wire current that it will not work with current signals 4-20 mA from active sources (calibrator with batteries)?

Thanks in advance

Yes.

2-wire = the module supplies the power to the transmitter, so the transmitter is 'passive'

4-wire = the transmitter has an external power source so it is 'active'

Note: In 2-wire the module doesn't 'generate' 24VDC to power the transmitter - you still have to connect a 24VDC source to the module at the appropriate terminals.

Ken

Thanks for reply Ken.
Your note:
"Note: In 2-wire the module doesn't 'generate' 24VDC to power the transmitter - you still have to connect a 24VDC source to the module at the appropriate terminals."
confused me a little.
I just want to be sure about one thing:
I expect that module does generate power supply to transmitter in 2-wire configuration, so because of that reason I assume that active current lopp will not working. But is it possible to make 2-wire module to work correctly with calibrator (with batteries) without connecting module to 24 VDC, since current loop is active?
In other words, is there any way to make 2-wire configuration to accept active current signal (from external source, calibrator)?

I'm little confused about this matter.
Thanks

Pandiani

I've told you all I know about making this connection work. And you confirmed it was working correctly when you had it set to 4-wire and used your calibrator. Why do you want to change the setting to 2-wire when we both know this doesn't work?!?!?

There is no pwer source inside any Siemens analog input modules that I've ever heard of. Why do you expect the module to generate the power signal? The wiring diagram is quite clear about where an external 24VDC source should be connected if you do genuinely have a 2-wire transmitter at any of the channels. The module then simply routes this power to the appropriate 2-wire channels, and blocks it from any channels configured as 4-wire because they have their own power source.

Don't think of the module as being 2-wire or 4-wire. There will only ever be two wires between the transmitter and the module. When you select 2-wire or 4-wire you are defining the type of transmitter connected at that channel.
"2-wire" means that the transmitter only has two wires (or terminals), and since they come from the module it (the module) has to provide power and read the signal over these two wires.
"4-wire" means that the transmitter has four wires or terminals connected to it - two of them will connect to the module to deliver the measured signal; two of them will be connected to a power source.

Regards

Ken

analog input module configuration via siemens PG 710

Hello guys,
1- I have a problem with S7-300 PG 710. the analog input module 8x12bit 6ES7 331-1KF01-0AB0 i want to configure because 0 - 10 vdc signal is availble in this module. unfotunately this module is not showing the same module in my PG.

2- i have converted the S5 program into S7 through S5-S7 converter. in this program some scaling modules were also converted FB250 and FB251. during Step 7 i am unable to simulate input signal on BG & KNKT.

Is there any way to make those two point be cleared?

Thanks

amjad

Start a new thread with your two questions rather than post a reply onto another thread.

To attempt to answer your questions....

1. Did you select the correct module from the hardware library? have you got the correct GSD file for the module?

2. FB250 and FB251 are analogue read and write to certain modules in step 5, in theory, you don't need to use these in step 7 because you can read and write directly to analogue I/O.

What version of step 7 are you using?

Paul

amjad.hayee said:

the analog input module 8x12bit 6ES7 331-1KF01-0AB0

Click to expand...

That part number is for a 13bit analogue input module, not 12bit, so are you sure you selected the correct module?

Paul

It should work to use a battery powered tester with either 4DMU (C) or 2DMU (D) set.
What is important is that the 4-20mA signal enters the same terminal as the normal analog signal, AND that the minus from the tester is returned via the same ground that the analog module shares.
Selecting measuring module = "C" means that the module is connected to ground.
Selecting measuring module = "D" means that the module delivers +24V.

If pandiani is connecting to some terminals that are wired to the module with the measuring module set to "D" then he has to take care that minus-wire from the tester goes to common ground and not the +24V that comes from the module.