HMP155 USB Interface Commands

Procedure

• Connect USB HMP155 reader to toughbook
• Connect up with Putty as shown below.
• type ? to get serial number, last calibration date & add them to spreadsheed.
• if unit is known to be ready to send back for recalibration, go ahead. If state is unknown...
  • connect to CR800/1000 running 1hz measure AT & RH program. Cup sensor head and blow hot moist air on it until RH% goes to 100+. If it shorts out, make a note for repair. If it continues to work then no notes, just send for recalibration.

HMP155 Status

• Labels may drift out of date with time. But:
• Yellow cap on = Newly calibrated HMP155
• Yellow cap off = Probably in need of Calibration

Background

You can use a special USB cable from Vaisala to check on the performance of an HMP155. To communicate, first install the driver. This is easier said than done but 'vaisala instrument finder' in google may get you close, then download directly from Vaisala. I can only find it via google, not through searching the Vaisala online software downloads. Also handy is the user manual:

• [check dropbox]

Check in the Device manager to see which COM port the cable installed as. For me it is listed as COM3. You can also see if you start CSI's Device Config. It shows up there as 'Vaisala USB Device COM3'.... however, the commsettings are not compatible with Device Config so you'll need to try Putty. The settings should be:

• 4800 Baud
• Even Parity
• 7 Data Bits
• 1 Stop Bit
• No hardware flow control

Plug everything in and here a few commands to try:

vers -- Version of probe
smode run -- start automated output of current sensed values
smode stop -- stop automated output
seri -- set the baud etc
? -- I got a read out of last calibration date, serial number and such.
?? -- same but while in polling mode.
help == Lists teh available commands

Check the manual for much more. All of chapter 4 covers things you can do from this interface.

Super Site Specific

Default from the factory will be the above: 4800 / E / 7 1

Baud P D S     :     4800 E 7 1

To work with the MD-485 type the following.

seri 9600 n 8 1

This will be the response:

Baud P D S     :    9600 N 8 1

Next, change the format of the default message:

FORM 5.3 T " " RH \n

The Default is:

RH= 27.6 %RH T= 26.7 'C

Changing the format results in this:

   17.164    49.757

Lost to history but I'm sure there is a reason, the MD485 has baud rate 19200 for talking RS232 with CR1000 but 9600 baud talking to HMP155.