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| 2/5/2008 6:54 AM | |
Joined: 9/27/2006 Last visit: 11/12/2024 Posts: 12293 Rating:
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Hello fro; Definition of wire-break detection for s7-300 analog modules: (from the S7-300 module data manual) Line continuity checkThe line continuity check is available for the 1 V to 5 V and 4 mA to 20 mA ranges.Rule for both measuring ranges: When the line continuity check is enabled, the module logs the wire-break to diagnostics data when the current drops below 3.6 mA (0.9 V.)The module also triggers a diagnostics interrupt if this function is enabled in the program. (see OB40 below) A wire break can only be signaled by means of the lit SF LED and the diagnostic bytes mustbe evaluated in the user program if diagnostics interrupts are disabled.When line continuity check is disabled and diagnostic interrupts are enabled, the module triggers a diagnostics interrupt when underflow is detected S7-300 analog input modules that offer wire-break detection 6ES7331-7NF00-0AB06ES7331-7NF10-0AB0 6ES7331-7HF0x-0AB0 6ES7331-7KF02-0AB0 6ES7331-7KB02-0AB0 6ES7331-7PF01-0AB0 6ES7338-4BC01-0AB0 Using OB40 in your program (Hardware Interrupt OB) from the Programming with Step 7 manual: 4.2.4.4 Hardware Interrupt Organization Blocks (OB40 to OB47)The S7 CPUs provide hardware interrupt OBs that react to signals from themodules (for example, signal modules (SMs), communications processors (CPs),function modules (FMs)). With STEP 7, you can decide which signal from aconfigurable digital or analog module starts the OB. With CPs and FMs, use theappropriate parameter assignment dialogs. Hardware interrupts are triggered when a signal module with hardware interruptcapability and with an enabled hardware interrupt passes on a received processsignal to the CPU or when a function module of the CPU signals an interrupt. Assigning Parameters to Signal Modules with Hardware Interrupt Capability Each channel of a signal module with hardware interrupt capability can trigger ahardware interrupt. For this reason, you must specify the following in the parametersets of signal modules with hardware interrupt capability using STEP 7: • What will trigger a hardware interrupt. • Which hardware interrupt OB will be executed (the default for executing all hardware interrupts is OB40).Using STEP 7, you activate the generation of hardware interrupts on the functionblocks. You assign the remaining parameters in the parameter assignment dialogsof these function modules. You will have to evaluate the local data of the OB40 (when it is called by a wire-break on one of your analog inputs) in order to set bits in the PLC (inside the OB40 program, for example)that you can use in the HMI to trigger messages, alarms, etc… see the following attachment for information on OB40 (from the System and standard functions manual) You can also look at the dollowing FAQ: http://support.automation.siemens.com/WW/view/en/6772626 |
Last edited by: dchartier at: 05.02.2008 07:52Last edited by: dchartier at: 05.02.2008 06:59 |
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