s7-300 Retentive Memory

FAGARCIA · Sep 29, 2007

Hello people.
How do I make some memory area keep the values on a power outage.
I'm using the set command on a coil, when I cycle power it goes back to zero.
I'm looking for something similar to latch coil on rslogix
I am using CPU 314C-2DP.

thanks.

reymond_craig · Sep 29, 2007

hi,

I don't know if if there's other way but I did something customize fb that act like a retentive timer. Tell me if fb is fine for you and i'll post the block.

warm regards,
Rey

L D[AR2P#0.0] · Sep 29, 2007

The default setting for the CPU is to retain the first 16 marker bytes.
Use one of these bits instead of the coil, then drive your coil with the marker bit. (The number of retained markers can be extended using the H/W config editor, refer to CPU properties)

FAGARCIA · Sep 29, 2007

I changed the default from 16 to 255 and it is working.
but in the module information on the memory tab the amount of retentive memory did not change. It stay at 14% even after I change the mb from 16 to 255. Doesn't sound right to me. see pic

L D[AR2P#0.0] · Sep 29, 2007

What does the byte count show ?

9214 bytes used (255 retained) = 14.060 % (rounds down to 14%)
8975 bytes used ( 16 retained) = 13.695 % (rounds up to 14% for display)

s7-300 Retentive Memory

FAGARCIA

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reymond_craig

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L D[AR2P#0.0]

Lifetime Supporting Member

FAGARCIA

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L D[AR2P#0.0]

Lifetime Supporting Member

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