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Transmitting ASCII text from CM1241 RS232 Comms Module

Created by: Mark W at: 10/13/2009 10:45 PM (2 Replies)

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10/13/2009 10:45 PM	Rate (0)
Mark W Advanced Member Joined: 9/24/2009 Last visit: 1/15/2025 Posts: 2 Rating: (0)	Hi, I have recently tried connecting a GSM Modem (Siemens TC35) to the CM1241 RS232 Module (6ES7241-1AH30-0XB0) in order to send SMS messages.I am using the SEND_PTP instruction to send AT commands to the TC35. The block functions correctly (the Transmit Light flickers when I issue the command) but the TC35 does notfunction as expected. I used Hyperterminal tomonitor what I was transmitting from the CM1241and found that each STRING was preceded by two non ASCII characters (i.e. ATE0 became ◊▫ATE0). However, when I changed the data type of the Static (assigned to the BUFFER input on the SEND_PTP instruction) from STRING to DOUBLE WORDand defined it as 16#41544530 (ASCII code for ATE0) all worked fine!! Can anyone explain why the transmitting a 'STRING' causes this problem? Many thanks, Mark W

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10/14/2009 3:39 PM	Rate (0)
kcross Posts: 1 Rating: (0)	The formal definition of a SIMATIC string includes 2 leading bytes,the maximum stringlength and the current string length. These are the 2 bytes that are preceding the actual string information. You may consider using either a byte array or character array instead ofa string.
kcross Posts: 1 Rating: (0)
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10/14/2009 3:57 PM	Rate (0)
Mark W Advanced Member Joined: 9/24/2009 Last visit: 1/15/2025 Posts: 2 Rating: (0)	Hi, Thanks for the quick response, I will try your suggestions. Mark W

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