How do I tare and zero using my HI 200DNWM?

Our 200DNWM is having problems issuing Tare/Zero commands over the DeviceNet from a Contrologix PLC.

Also, we wish to set up a system through the SCADA by which a supervisor can calibrate the unit.

Your HI 200DNWM module uses 2 byte integer registers. To Tare/Zero the first word would be byte 0 (least significant byte) and byte 1 (most significant byte). Second word would be byte 2 (least significant byte) and byte 3 (most significant byte).

Different PLC systems use a 32 bit double integer and combine these two words. You need to know the order of the bytes to know where to place which piece of data. We would recommend you set up a double integer with a value of 04030201 hex in it. Then copy this double integer into two single integer locations and see what value shows up where. This way you can see each byte by the value placed in it. Once you know this order, you will then know the order needed for the HI 200DNWM module commands.

Once you know where the bytes are located, you can place the proper data in each to run a command. To run the Tare or Zero command, you would place a value of:
1 into byte 0
0 into byte 1
18 (tare) or 19 (zero) into byte 2
1 into byte 3.  (write cmd)

Once this command has been run, you would need to resend the command with the data byte 0 set back to a value of 0.  If this is not done, the next time you try to run the command, it will not operate, since the module is looking for the 0 to 1 transition.  If you fail to set the value back to zero, then it will already be at a value of 1 and module will not see the 0 to 1 transition.

This would then do the command requested. Other commands, like the calibration commands, would follow this same format and run the same way. Just change the parameter ID in byte 2 to be the new parameter you want to change and place the new data into bytes 0 & 1.

Trying to set up a SCADA unit to run the commands would entail having the SCADA unit talk to the DeviceNet master. Then this master would send the command to the HI 200DNWM following the above format.