Siemens Simatic S7-200 System Manual page 426

Special Memory (SM) Bits
Table D-15
SM Byte
SM67.4 and
SM67.5
SM67.6
SM67.7
SMB68
SMB69
SMB70
SMB71
SMB72
SMB73
SMB74
SMB75
SM76.0 to
SM76.5
SM76.6
SM76.7
SM77.0
SM77.1
SM77.2
SM77.3
SM77.4 and
SM77.5
SM77.6
SM77.7
SMB78
SMB79
SMB80
SMB81
SMB82
SMB83
SMB84
SMB85
SMB86 to SMB94, and SMB186 to SMB194: Receive Message Control
As described in Table D-16, SMB86 through SMB94 and SMB186 through SMB194 are used
to control and read the status of the Receive Message instruction.
D-10
Special Memory Bytes SMB66 to SMB85, continued
Reserved
PTO0/PWM0 mode select: 0 = PTO, 1 = PWM
PTO0/PWM0 enable bit: 1 = enable
PTO0/PWM0 cycle time value
SMB68 is most significant byte, and SMB69 is least significant byte.
PWM0 pulse width value
SMB70 is most significant byte, and SMB71 is least significant byte.
PTO0 pulse count value
SMB72 is most significant byte, and SMB75 is least significant byte.
Reserved
PTO1 pipeline overflow: 0 = no overflow, 1 = overflow
PTO1 idle bit: 0 = PTO in progress, 1 = PTO idle
PTO1/PWM1 update cycle time value: 1 = write new cycle time
PWM1 update pulse width value: 1 = write new pulse width
PTO1 update pulse count value: 1 = write new pulse count
PTO1/PWM1 time base: 0 = 1 µs/tick, 1 = 1 ms/tick
Reserved
PTO1/PWM1 mode select: 0 = PTO, 1 = PWM
PTO1/PWM1 enable bit: 1 = enable
PTO1/PWM1 cycle time value
SMB78 is most significant byte, and SMB79 is least significant byte.
PWM1 pulse width value
SMB80 is most significant byte, and SMB81 is least significant byte.
PTO1 pulse count value
SMB82 is most significant byte, and SMB85 is least significant byte.
Description
S7-200 Programmable Controller System Manual
C79000-G7076-C230-02