Program instructions
7.7 Pulse output
S7-200 SMART
System Manual, 09/2015, A5E03822230-AC
253
Ensure that you understand the definition of the PTO/PWM mode select bit (SM67.6,
SM77.6, and SM567.6). The bit definition may not be the same as some legacy products
that support a Pulse instruction. In the S7-200 SMART, the user selects PTO or PWM
mode with the following definition: 0 = PWM, 1 = PTO.
When you load a cycle time/frequency (SMW68, SMW78, or SMW568), pulse width
(SMW70, SMW80, or SMW570), or pulse count (SMD72, SMD82, or SMD572), also set
the appropriate update bits in the control register before you execute the PLS instruction.
For a multiple segment pulse train operation, you must also load the starting offset
(SMW168, SMW178, or SMW578) of the profile table and the profile table values before
you execute the PLS instruction.
If you attempt to change the time base of a PWM output while the PWM is executing, the
request is ignored and a non-fatal error (0x001B - ILLEGAL PWM TIMEBASE CHG) is
created.
Table 7- 10 SM locations for the PTO/PWM control registers
SM66.4 SM76.4 SM566.4 PTO delta calculation error (due to an add error):
• 0 = No error
• 1 = Aborted due to error
SM66.5 SM76.5 SM566.5 PTO profile disabled (due to user command):
• 0 = Profile not manually disabled
• 1 = User disabled profile
SM66.6 SM76.6 SM566.6 PTO/PWM pipeline overflow/underflow:
• 0 = No overflow/underflow
• 1 = Overflow/underflow
SM66.7 SM76.7 SM566.7 PTO idle:
• 0 = In progress
• 1 = PTO idle
SM67.0 SM77.0 SM567.0 PTO/PWM update the frequency/cycle time:
• 0 = No update
• 1 = Update frequency/cycle time
SM67.1 SM77.1 SM567.1 PWM update the pulse width time:
• 0 = No update
• 1 = Update pulse width
SM67.2 SM77.2 SM567.2 PTO update the pulse count value:
• 0 = No update
• 1 = Update pulse count
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