Siemens SINUMERIK 840D sl Function Manual

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Detailed description2.7 Structure and functions of the basic programBasic logic functions: PLC basic program solution line (P3 sl)Function Manual, 11/2006, 6FC5397-0BP10-2BA0 49Control/Status signalsA shared feature of the control and status signals is that they are bit fields. The basicprogram updates them at the start of OB1.The signals can be subdivided into the following groups:• General signals• Mode-groupspecific signals such as operating modes• Channelspecific signals such as program and feed modifications• Axis- and spindlespecific signals such as feed disableAuxiliary and G functionsThe auxiliary and G functions have the following characteristics:• Transfer to the PLC is blocksynchronous (referred to a parts program block)• Transfer is acknowledgedriven.• The acknowledgment times have an immediate effect on the execution time of NC blockscontaining auxiliary functions requiring acknowledgment.The value range is presented in the table below:Function Structure Range of values Data type1. Value 2. Value 1. Value 2. Value 1. Value 2. ValueG function G function 255 1) ByteM word M group M word 99 99.999.999 Word DWordS word Spindle no. S word 6 Floatingpoint 2)Word DWordT word Magazineno.T word 99 65535 Word WordD word - D word 99 255 Byte ByteH word H group H word 99 FloatingpointWord DWordF word Axis No. F word 18 FloatingpointWord DWord1) relative number, transferred for each G group2) corresponding STEP 7 format (24-bit mantissa, 8-bit exponent)The M, S, T, H, D and F values sent by the NCK are output together with the accompanyingchange signals to the CHANNEL DB interface via the auxiliary/G functions (seedocumentation "Lists of SINUMERIK 840D sl"). The function value and the extendedaddress are transferred to the appropriate data word. The accompanying modification signalis activated to 1 for one PLC cycle. When the modification signal is reset, theacknowledgment is passed to the NCK. The acknowledgment of highspeed auxiliaryfunctions is given by the basic program immediately the basic program detects the auxiliaryfunction.In addition to distribution of the auxiliary and G functions, selected signals are processed asdescribed below.