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Weight Scale Interfacing Example: Digi
D770 The following script communicates with a Digi Model D770 weight scale. During invoicing or other transaction related activities a function key can be programmed to launch the script below, using the ScriptRun() function. Example Interfacing Script * D770 scale interface DECLARE nWeight TYPE Numeric DECLARE cResponse TYPE String DECLARE cDevice TYPE String nWeight := 0 cResponse := "" cDevice := "D770" * IF ComOpen(cDevice) * ENQ If .Not. ComWrite(cDevice, Chr(5)) Goto ERROR Endif * read response ( 1 char, no terminator, wait max.1 sec ) cResponse := ComRead(cDevice, 1,, 1) If IsEmpty(cResponse) Echo("No response from the scale") Goto ERROR Endif * * NAK received If cResponse == Chr(21) Echo("Transmission error") Goto ERROR Endif * * NUL received If cResponse == Chr(0) Echo("Scale not stable") Goto ERROR Endif * * CAN received If cResponse == Chr(24) Echo("No new weight on the scale") Goto ERROR Endif * * ACK received If cResponse == Chr(6) * request the weight - send DC1 If .Not. ComWrite(cDevice, Chr(17)) Goto ERROR Endif
* wait for up to 9 characters, timeout 1 sec. cResponse := ComRead(cDevice, 9,, 1) If IsEmpty(cResponse) Echo("No response from the scale") Goto ERROR Endif
* NAK received If cResponse == Chr(21) Echo("Transmission error") Goto ERROR Endif
* ACK received (unexpected) If cResponse == Chr(6) Echo("Transmission error") GoTo ERROR Endif
* end of transmission If cResponse == Chr(13) Goto ERROR Endif
If Len(cResponse) == 9 nWeight := Val(Substr(cResponse, 3, 5 )) / 1000 Endif Else Echo("Unknown response from the scale") Goto ERROR Endif Endif
:ERROR If .Not. Empty(ComError(cDevice)) Echo(ComError(cDevice)) Endif ComClose(cDevice) * echo(Str(nWeight)) Return nWeight ____________________________ Related Topics Serial Communication Functions
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