Patent ID: 8766621
Filing Date: 2014-07-01
Classification: G05B

Abstract:
1. A method for operating an analog input module in a programmable logic controller, the analog input module having a ground potential for a channel output, for a first channel input, for a second channel input and for a third channel input, the method comprising: connecting a two-wire measuring transducer to the channel output of the analog input module and to the first channel input of the analog input module; connecting a four-wire measuring transducer to the first channel input of the analog input module and to the second channel input of the analog input module; connecting at least one further measurement circuit to the second channel input and to the third channel input of the analog input module; generating a first electrical potential which is present at the channel output using a transformer device; generating a second electrical potential which is present at the first channel input using the transformer device, an absolute value of the second electrical potential being less than an absolute value of the first electrical potential and greater than an absolute value of a ground potential; and generating a current for performing a functional test of the connected two-wire measuring transducer as a result of a potential difference between the first electrical potential and the second electrical potential.