Deana,
If you can access the device via Hyperterminal, read register 20 by typing:
**R20 (followed by a carriage return)
The device should respond with the text of the register's 16-bit value as a decimal number.
The best way to approach this is to think of the value as a bitfield; the info I've pasted below shows most of the bits that comprise the selection options for that register.
Looks like you want to change the device from a mass controller to a pressure controller. That's esssentially a three-bit field at bits 10 thru 8.
If you want to control upstream rather than downstream pressure, you'll also want to set bit 15 to invert the PID loop.
You will almost certainly need to retune the loop parameters after having changed this... registers 21, 22, and 23.
Edit: Ooops. In Hyperterminal, write a new value to register 20 by typing:
**W20=<nnnnn> followed by a carriage return, where <nnnnn> is the new value as a decimal number.
PM me if any of this is unclear.
Best regards,
Dave
Bit(s) Set Clear
bit 15 Vacuum/Back Pressure Pressure
bit 14 Analog Setpoint RS232 Setpoint
bit 13 Auto Tare No Auto Tare
bit 12 4-20 mA Setpoint 0-5V Setpoint
bit 11 Local (Front Panel) Setpoint Analog or RS232
bit 10-8 Controller Select
100b = Mass Flow
011b= Volumetric Flow
010b= Temperature
001b= Pressure
000b= No Controller
David Boyd
Sr. Test Engineer
Abbott Labs
(lapsed) Certified LabVIEW Developer
