The Industrial Raspberry Pi Forum

Hi,

I am having an issue reading any of the Process Image byte variables ... ie. DIn_Status, DOut_Status, RevPiLED all return 00000000 regardless of the actual state.

Example
Success - Activates OUT 0 LED on the unit
Success - Returns "1"
Fail - Returns "00000000"
I Expected - "10000000" from this. Have I got something wrong here? How can I read all the DOut_x bits in one piTest command?

I posted about this last week here viewtopic.php?f=6&t=2884#p10472, but still haven't got a response. I'm really hoping someone can help me here as I've got quite a tight deadline to get this project working. I've also just plugged in a ModBus slave and am having a similar issue with that... I can read BOOL variables ie Input_Bit_1 = 1 but not WORD variables ie Input_Word_1 = 00000000 00000000.


Thanks for any suggestions!

Additional issue: Modbus_Actions_Status errors not resetting

The example below is for an action configured as follows

Action #2 | 95 | READ_HOLDING_REGISTERS | 40004 |1 | 1000 | Input_Word_7


1. This returns "2"
I understand 2 = ILLEGAL DATA ADDRESS

2.
I now want to reset the error code on Modbus_Action_Status_2 so that I can try a different address and check if the error is reported again.
I remove Action 2 from the Extended Data GUI so that the error is not regenerated while poling, then... This returns "Set bit 1 on byte at offset 207. Value 1"

3. This still returns "2"
I expected this would be 0

Modbus_Master_Status is 0 the whole time. The variable Input_Word_7 is also 0 the whole time. I am able to read the addresses 40004 the slave fine using a gui on my PC and it returns 5. I was also able to read 40004 using minimalmodbus on the revPi, but I had to use "Raw Address" "3" rather than 40004. I'm not sure if this Raw Addressing is common or something particular to the monnit gateway I am working with.

Hi

livesource wrote: ↑28 Jun 2021, 05:39

Code: Select all

piTest -1 -q -r DOut_Status,b

Fail - Returns "00000000"
I Expected - "10000000" from this. Have I got something wrong here? How can I read all the DOut_x bits in one piTest command?

Why do you expect a different value than 0? Extract from the wiki:

Hi,

please remove any register configuration and restart the modbus driver / reset the action. Is it still != 0?

Regarding the raw address: I have a Modbus RTU meter connected to my RevPi and having the same issue that the register address is specified with 30007, but I have to use 7 in order to get data. Ihmo this comes from the original Modbus specs which where written with Modicon controllers in mind where the function code was encoded in the address.

Nicolai

I think that some of the issues I've been experiencing are related:

viewtopic.php?f=6&t=2905

Could there be something about Modbus registers with 5 digits being mishandled somehow?

It would be great to know what is causing this issue and if it's a piTest issue or something else.