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Serial ASCII Comms issue


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Guest NobbyDooDaa
Posted
I am having problems communicating with some Overhead Text displays. I'm new to this PLC programming malarky (& RS422 comms) so first I wrote a test program on my PC in VB to talk to the OHDs; which works fine but then I moved onto the PLC software.... Using the OUTPUT command I can send data (non-proceedure protocol) and see it arrive on my PC's comm. port (which is configured as the overhead display). The issue is that when I send a string 'ABCDEFG' I get gobbledigook arrive on my PC. From reading the manual it seems that I need to convert my string into binary data first (Haven't tried this yet as the PLC is now on site). However the overhead displays requires some control codes (eg 0xf0 or 0xf1 HEX) in their message format, that are part of the extended ascii charater set (0x00 - 0xff) but the only commads I can find are limited to the standard 8bit character set (0x00 - 07f). Has anyone got any ideas on how I might handle this? [i am using a Q12HCPU + QJ71C24N serial card with GX IEX Developer version 6.] TIA

Posted
- How much of a plonker do I feel! This is what happens when you don't take a rest! 0xff is 8 bits when you add them all up of course; so the HABIN & DHABIN functions should work fine. Thanks for not slating me.

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