M172 retain global variable error

jan4 · ‎2024-01-04

Hello,

I am trying to define a global variable as a Retain-Variable for M172 (TM172PBG42RI) in ESME HVAC by:

VAR_GLOBAL RETAIN

g_test : INT;

END_VAR

When I use g_test in my main program i receive the error

MAIN(28) - error A4100: g_test => Retentive vars space exhausted

while compiling.

Does anybody has a hint, what i am doing wrong?

I need the value to save the state of the program in case of a power failure on site.

Thanks in advance!

VaughnKretzmann · ‎2024-01-04

You need to use persistent variables for this.

Follow the link below:

Kind regards

Vaughn Kretzmann

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jan4 · ‎2024-01-05

Thanks for your guess, but in ESME HVAC "Persistent" is not allowed as a keyword.

Kind regards,

jan

LeTomas · ‎2024-01-05

I believe the best for you is to use the EEPROM variables:

The retain / persistent area of variables in the M17x is not like the PLCs M241,M251 or M262 as @VaughnKretzmann mentioned.

Best regards,

LeTomas