Measuring a slot with a multi-meter.

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Split from I/O slots and addressing.

CaOd,

• I am using an S7-1500 (1512C-1 PN) for control of a security barrier system in my facility. It is programmed to receive various commands from a PC running a program that I wrote in order to control various functions. This all works very well.
• The I/O modules are integrated into the PLC unit. I'm only using one of the digital I/O modules, labelled DI 16/DQ 16 x 24VDC
• Let's say, for example, that I have a function that energizes the coil output 0 on the digital module (with the correct address of course) and the light for that slot comes on, which I have successfully achieved. Shouldn't I see 24V measured at that slot in reference to ground?

Have you compared your wiring to the reference drawing for that module?

https://support.industry.siemens.com/cs/mdm/83501523 then open the wiring -> wiring & block diagram section.

Note it has 2L+, 3L+, 1M, 2M, 3M 

i_was

CaOd,

• I am using an S7-1500 (1512C-1 PN) for control of a security barrier system in my facility. It is programmed to receive various commands from a PC running a program that I wrote in order to control various functions. This all works very well.
• The I/O modules are integrated into the PLC unit. I'm only using one of the digital I/O modules, labelled DI 16/DQ 16 x 24VDC
• Let's say, for example, that I have a function that energizes the coil output 0 on the digital module (with the correct address of course) and the light for that slot comes on, which I have successfully achieved. Shouldn't I see 24V measured at that slot in reference to ground?

huggy,

I viewed the diagram in your link. Does this mean when I activate (for example) slot 21, the voltage should read 0V in reference to ground but in reference to slot 29 I should read 24V?

Regards,

Ian

Between the time I posted my link and now, it suddenly points to some cloud connector instead of the 16DI/16DQ for s7-1500, part # 6ES7523-1BL00-0AA0.

Wha is slot 21?

There are 16 digital inputs and 16 digital outputs.

Terminal 21 represents the 1st digital output.

For that output to work correctly, you have to know the address assigned to the module, found in the device properties for that device (among other places).

You need 1M, 2M, and 3M connected to the - connection on your 24VDC power supply.

You need 2L+ and 3L+ connected to the + connection on your 24VDC power supply.

After you do that, you can then monitor the output address of the module, let's say it is your first I/O module connected right next to the PLC with the backplane connector in place, and the addresses for the outputs are byte 0..1, or Q0.0 to Q1.1.

Now you can configure your logic to toggle Q0.0 every 2 seconds, which is easy if you use the provided system clock memory byte.

Now you put your multimeter in voltage mode and probe wiring in the correct meter connections for measuring voltage.  With - probe on -24V DC power supply (or pin 2M on your module), and + probe on Q0.0, you should read almost 24VDC for 1 sec, then 0 VDC for 1 sec, and repeat forever.

The indictor for output 0 should also toggle on and off every second, each state lasting 1 second.

The clock memory bit to do that is named by default 0.5_clock or something similar.

i_was

huggy,

I viewed the diagram in your link. Does this mean when I activate (for example) slot 21, the voltage should read 0V in reference to ground but in reference to slot 29 I should read 24V?

Regards,

Ian