ABB 620 Series ANSI, Manual

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Section 3
1MAC052634-MB D
Vendor-specific implementation
22 615/620 series ANSI
Communication Protocol Manual
The double point select-before-operate mode is usually used for the circuit breaker
operations. It consists of four controllable objects:
• Select open
• Select close
• Cancel selection
• Operate (=execute) selection
Direct operate of a double point object consists of two controllable objects:
• Direct open (writing a “1” value opens the circuit breaker, writing a “0” value closes
the circuit breaker)
• Direct close (writing a “1” value closes the circuit breaker, writing a “0” value opens
the circuit breaker)
3.3.6.1 Control functions
Only controls made through 4x register structures are supported in RE_615 ANSI. The
circuit breaker can be operated via Modbus by using a function codes 06,16 or 23.
Only one control bit can be operated at a time when the 4X control structures are used.
Exception codes
Only a few exception code alternatives exist for the write coil and write register requests
in Modbus:
• 01 = illegal function
• 02 = illegal address
• 03 = illegal value
The exception code 03 is also returned if a command operation is rejected due to the IED's
other internal reasons. The client can find the code for the internal rejecting reason in the
SSR6 register.
Internal control rejection reasons with coils may be, for example:
• The client has no write authority.
• The IED is in local state.
• The control operation is already reserved by another client and thus blocked.
If a positive acknowledgement is returned, the control command has been initiated by the
IED.
An output cannot support both direct-operate and select-before-operate
modes at the same time.
Direct operate of a double point object is always possible.
Select-before-operate control is possible if the controllable object's control
model is set to “sbo-with-enhanced-sequrity”.