From S7-1200 Easy Book:

4 Pulse Train Output rates

CPU: 100 KHz max.,2 Hz min.

SB: 20 KHz max., 2 Hz min.

Special SB: 200 kHz max., 2 Hz min.

For CPU models with relay outputs, you must install a digital signal board (SB) to use the pulse outputs.

--- For special modules ---
The high-speed (200 kHz) SBs utilize "sourcing" inputs. The standard SB (20 kHz) utilizes
"sinking" inputs. Refer to the specifications for the digital inputs and outputs (Page 256).
The high-speed (200 kHz) outputs (SB 1222 and SB 1223) can be either sourcing or sinking.
For sourcing outputs, connect "Load" to "-" (shown). For sinking outputs, connect "Load" to
"+". Because both sinking and sourcing configurations are supported by the same circuitry,
the active state of a sourcing load is opposite that of a sinking load. A source output exhibits
positive logic (Q bit and LED are ON when the load has current flow), while a sink output
exhibits negative logic (Q bit and LED are OFF when the load has current flow). If the
module is plugged in with no user program, the default for this module is 0V, which means
that a sinking load will be turned ON.
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There is a note related to high speed digital inputs that may help with your PTO real world output rate between the PTOs and the device receiving the signal.
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NOTICE

When switching frequencies above 20 KHz, it is important that the digital inputs receive a

square wave. Consider the following options to improve the signal quality to the inputs

Minimize the cable length

Change a driver from a sink only driver to a sinking and sourcing driver

Change to a higher quality cable

Reduce the circuit/components from 24 V to 5 V

Add an external load at the input