Reference Manual Owner's manual

Rockwell Automation Publication 750-RM001F-EN-P - February 2012 21

Safety Concept Chapter 1

Output Pulse Test Considerations

If the pulse testing of any safety output is disabled, the maximum safety rating

will be up to and including SIL CL2, PL d, and CAT 3 for any safety chain

incorporating any input or output of the safety option.

You may need to disable pulse-testing if the connected device does not support

OSSD inputs. Refer to the product documentation for your connected device.

Encoder Considerations

When configured correctly, the safety option performs these diagnostics on the

encoder:

• Sin

+ Cos

diagnostic

• Detection of open or short-circuit

• Encoder supply voltage monitoring

• Detection of illegal quadrature transitions of the sine and cosine signals

You can use motors that use a single-encoder application if they meet the

following criteria:

• Motor is a Permanent magnet (PM) brushless AC motor

• Motor controller utilizes the single encoder for control of IGBT firing

(commutation)

• Controller is not configured for auto transition to encoderless

commutation in the event of encoder failure

• Encoder is of the Sin / Cos type

• Motor / Encoder coupling is designed so as to exclude shaft slippage as a

failure mechanism (optional – such as tapered fittings)

IMPORTANT

Setting any of the P72 [SS Out Mode], P73 [SLS Out Mode], or P74 [DC Out

Mode] parameters to 1 = No Pulse Test disables internal diagnostics as well as

external diagnostics required to achieve higher safety ratings.

You must exercise the SS_In input at least once every six months.