GE VERSAPRO and FIRST_PASS

A

Thread Starter

Andy

Unlike Allen Bradley GE VERSAPRO does not have a FIRST_PASS instruction, also known as "ON_POWER_ON" on some other PLC.

Does anyone know how to achieve the behavior using any other instruction with GE VERSAPRO software, I'm using the micros and the 90-30'S PLC.

I need to perform a function only once, when the PLC has been turned on for the first time.

Thanks

Andy

Puerto Rico
 
A
I thought that %s1 was the FIRST_PASS bit that you require.
If not then simply use a normally closed contact of any internal bit and then set the coil of this bit on at the end of your code.
If you only want it to happen on the first power up and not subsequent power ups, then use a retained on power down bit.
Simple, but should work if %S1 does not exist.
 
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Joe Jansen/ENGR/HQ/KEMET/US

A good generic method of doing this is to use a non-retentive (ie, "forgets" it's last state during a power off condition) coil, and as the very *last* rung of logic, have an unconditional output turning on that coil.

In the program, test for the coil to be de-energized. If it is, you are on your first scan. If it is energized, then the first scan has completed.

--Joe Jansen
 
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Bruce Durdle

Andy,
As the very last command in your ladder, have a coil that is energised directly from the power rail with no intervening contacts. For the duration of the first scan, this coil will be OFF, but for every subsequent scan it will be ON.

Bruce.
 
H

Hurd, David L (GEA, 053698)

In Series 90-30 the first scan bit is called FST_SCN and is at address %S0001.
Dave
 
R

Ricardo Ribeiro

Hi Andy,

What I used to do in an old GE PLC=B4s is add as the very last rung one coil which is permanently energised and use its normally closed contact as
"power-on reset".

Regards,

Ricardo Ribeiro
Alcan Aluminio do Brasil Ltda
 
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