How to input data from a peripheral
There are a multitude of third-party RS-232 peripherals that have made their home on the factory floor such as bar-code scanners, weight scales, force gauges, multi-meters and the like, which use a standard serial cable to send their data to a host PC. The Multi-Drop Peripheral Interface is a member of the Stackable DAQ Module's series and is designed specifically for these third-party devices, allowing them to be connected to the same serial cable as the other DAQ Modules. In fact, up to 32 of them can share the same cable and a single port on a PC.
A lot of these third-party devices transmit data at random, rather than being polled by the host which is the method used by the Stackable DAQ Module's. In addition, the format of the data which they are transmitting may be entirely different than the DAQ modules. Therefore, placing a Data Window on the screen and having it automatically poll for data will not work in this case. Fortunately with ModCom there is another option available which can be used to acquire data without polling and it also will not matter what type of data format is being used by the peripheral as long as it is standard ASCII characters. This is the Data Parser function and can be found in the <Run-Loop> menu at the top of the screen.
Using data parsing to capture serial data:
A Data Parser is a user defined parser routine which can monitor the serial port for any data which begins with a specific header character determined by the address setting of the Multi-Drop Peripheral Interface attached to the third-party peripheral. Once data arrives, the parser can extract one or more sections of the data stream and send it to Screen Objects or Variables within ModCom. See Data Parser for more info on how to set this up and use it.