01 PLC 5 Software Guide and Manual UnofficialPLC 5 Software Guide. 02 Any Station - Generic 03 Drawn – D J Ray 04 Original is A4 – Landscape. This document forms a guide to SFC programming that is common to Voith SFC Software. GCS Support.MERIDIAN ENERGY LTD.State Highway 8,Twizel,New Zealand.
General Guide Use a single SBR to connect all discrete digital inputs to a buffer file.Use a single SBR to connect all analog inputs to a RAW (un scaled) buffer file.Use a single SBR to scale all the analog inputs using CPT instruction – use either inline scaling values or references to a scaling data file.Make all unit (generator) code the same across a station – use the DH+ address as a switch to turn on and off unit specific functions.Use SFC’s where ever possible.Use standard/generic SFC’s where ever possible.Use 1 SBR file for 1 SFC where ever possible.Use 1 Data file for 1 SFC where ever possible – however its likely more than 1 will be needed often.Describe the inputs to the SFC – Digital and Analog.
SCADA ALARMING Every PLC Scan do this – the alarm is latched into N50:10 on for reading by scada– they are latched so that a fleeting alarm is held in N50 till scada acknowledges it has read the N50: fileWhen it does ack the alarm value perform a plain COP to freshen the N50 file N50:10 = N47:10 OR N50:10 (Lgt = 40 for N47:10 to N47:49) N47: N50: N50: Logical OR Indications – both bit and integer are not latched – the N50 file is addressed directly in code.
PLC 5 Code segement to perform scada Alarm Ack Value calculation and verification – and N50 re-freshing control. If scada ack’s the alarms – by returning a Alarm Ack set point hat equals theAlarm Ack Value as computed by the PLC – the scada has ‘seen’ the currentN50 file so freshen it. If scada has not ack’ed the current alarms – keep them and add any new ones. Initalization Compute a crude value that can be used to determine if the alarming file N47 has changed.Various symetrical bit patten alarm changes will not be detected. BST EQU N51:51 N50:51 BST COP #N47:10 #N50:10 40 NXB CLR N50:51 BND NXB NEQ N51:51 N50:51 XIO R6:0/EN FAL R6:0 40 0 ALL #N50:10 #N47:10 OR #N50:10 NXB XIO R6:1/EN BST CLR F46:0 NXB FAL R6:1 40 0 ALL F46:0 F46:0 + #N50:10 BND NXB NEQ F46:0 F46:1 BST ADD N50:51 1 N50:51 NXB MOV F46:0 F46:1 BND NXB GRT N50:51 1000 MOV 1000 N50:51 BND If the alarming file has changed – INC the Alarm Ack Value – this is passed to scada.Which will return it – indicating it has seen the current state of N50 House keeping Limiting – 1,000 is a lot of alarm changes.
VOITH CAN RTD Alarming & Tripping RTD’s Each Fault bit is derived by ths sort of rung A trip is derived like this Or a high alarm like this.
A SFC – Normally 1 per SBR but often more than one are found in a SBR A typical Voith SFC consists of the following code segments – in the following order.Inputs to SFCDerivedStep TimersStep ControlStep DecoderStep Outpts Typical overview of the code sctions that make up a SFCand the order and size they take in any one ladder file. Inputs to SFC Derived Step Timers Step Control Step Decoder Step Outpts
This is a standard Voith Step Decoder and Controller.N80 for step wordsB81 for step bitsB83:0 is a buffer location used by many SFC decoders.N7:100 is a buffer location used by many SFC decoders.Each step is guaranteed to be true for at lest one scan if the rule below is used…1:- Never used the step word for state tests – always use the step bit.