Siemens SIMATIC S7-300 Module data Manual page 533

STL
L PED 256
T MD 100
A M 100.7
= M 99.0
L PED 230
T MD 104
A M 104.7
= M 99.1
L PED 264
T MD 108
A M 108.7
= M 99.2
L MB 99
T POB 256
Explanation
// Read encoder value in the address area for encoder
input 0
// Save encoder value to memory double word
// Freeze state for subsequent acknowledgement
// Determine and save
// Read encoder value in the address area for encoder
input 1
// Save encoder value to memory double word
// Freeze state for subsequent acknowledgement
// Determine and save
// Read encoder value in the address area for encoder
input 2
// Save encoder value to memory double word
// Freeze state for subsequent acknowledgement
// determine and save
// Load freeze state and
// acknowledge (SM 338: output address 256)