1766-RM001A-EN-P MicroLogix 1400 Programmable Controllers ...

ASCII Instructions 375Entering ParametersEnter the following parameters when programming this instruction:• Channel is the number of the RS-232 port, Channel 0.• Control is the control data file. See page 365.• Characters are the number of characters in the buffer that thecontroller finds (0…1024). This parameter is read-only and residesin word 2 of the control data file.• Error displays the hexadecimal error code that indicates why the ERbit was set in the control data file. See page 390 for error codedescriptions.Addressing Modes and File Types can be used as shown below:ABL Instruction Valid Addressing Modes and File TypesFor definitions of the terms used in this table see Using the Instruction Descriptions on page 92.ParameterOISBT, C, RNData Files (1)FSTLFunction FilesMG, PDRI/RIXPLSRTCHSCPTOX, PWMXSTIEIIBHIMMILCDAddressModeAddress LevelCS - CommsIOS - I/ODLS - Data LogImmediateDirectIndirectBitWordLong WordElementChannel • •Control • • •(1) The Control data file is the only valid file type for the Control Element.Instruction OperationWhen the rung goes from false-to-true, the Enable bit (EN) is set. Theinstruction is put in the ASCII instruction queue, the Queue bit (EU) is set,and program scan continues. The instruction is then executed outside ofthe program scan. However, if the queue is empty the instruction executesimmediately. Upon execution, the Run bit (RN) is set.The controller determines the number of characters (up to and includingthe termination characters) and puts this value in the POS field of thecontrol data file. The Done bit (DN) is then set. If a zero appears in thePOS field, no termination characters were found. The Found bit (FD) isset if the POS field is set to a non-zero value.Publication 1766-RM001A-EN-P - October 2008