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2456-LEM, Laboratory Environmental Monitor, LEMcal software troubleshooting

Also see the LEM and LEMcal manual at this link, LEM manual or software download

You can download the current version of LEMcal software that is v1.08 at the same link.

Here is a video of LEMcal software with a LEM

The LEM does not have a display so it needs to be connected to a computer, either directly or though a PG Monitor or Autofloat controller. Because of this the most frequent issue wtih a LEM is that "it won't communicate." It is easiest to troubleshoot a LEM when it is connected directly to a computer's serial port and LEMcal is run on the computer.

This guide shows some tips for troubleshooting communication problems with a LEM.

The most common error is that the RS232 / RS485 switch on the back of the LEM is in the wrong position. RS232 is for direct communications to a computer and RS485 is for use when the LEM is connected to a PG Monitor or Autofloat controller. Make sure that the switch is set appropriately. Remove power to the LEM when changing this switch or remove power for a few seconds after changing the switch. Note that the switch can be a rocker switch or a sliding switch.

When a LEM is connected directly to a computer it needs its power adapter cable connected in addition to the 9-pin serial communications cable. Fluke part number 3723953 is a straight through 9-pin serial cable with female connectors on both end and is included with the LEM. Fluke part number 2758335 is the same but with one male end and one female end, and is not included with the LEM. Note that the serial cable must be a straight-through cable (not a null modem cable). If a USB to serial adapter is used make sure it is a good quality one and that the driver on the computer is successfully installed. On the computer, go to the Device Manager to check what COM port on the computer it has been assigned to because this will have to be entered in the LEMcal software.

Note that the additional 9-pin port labeled "Serial Pressure Input" is not used although instructions for its use are in the manual.

Follow the instructions in the manual to install and start LEMcal software. Then setup the serial port by the [Setup], <Communication> menu path. This is the COM port on the computer that the serial cable or serial to USB cable is connected to. Default COM settings for a LEM are: Baud rate 9600, Databits 8, Parity None and Stop bits 1. Communication protocal set to Binary.

The address of the LEM is set in the [Setup], <Options> screen in LEMcal. The default address is 33 but is sometimes changed to the last two digits of the serial number of the LEM. For example if the serial number of the LEM is 69421 the address should be 33 but may be 21. 

If those are unsuccessful, press the [Poll Address] button to have LEMcal try all possible addresses. In the below example LEMcal found a LEM with address 33.

In the [Setup], <Options> screen you can also try the universal address that is zero (0). Note that the universal address zero (0) works in LEMcal but not in WinPrompt. If the address is zero (0) then you must change it if you will use the LEM in WinPrompt (keep reading).

If you like you can change the address in the [Calibrate], <View Coefficients> screen by double-clicking on the Address. When you're done editing the address, click the "Write coefficients to sensor" icon. A small window will flash showing that this worked, but sometimes LEMcal freezes after this. If so, close LEMcal and check if if worked. Note that changing the address is more reliable using LEMcal v1.07. LEMcal v1.07 can be downloaded below if you only have the current version that is v1.08. 

In the [Setup], <Options> screen, the Pressure Source should always be set to "Local".

If you prefer you can test with a communications program like HyperTerminal. Remote settings are 9600 baud rate, 8 databits, none for parity and 1 stop bit. Communication protocal set to Binary. Send this command $00015275 and the reply should be a 21 characters starting with exclamation point (!) then two numbers that are the address of the LEM (for example !33).

Once you establish communications directly with a computer with LEMcal you can note the address and attempt to communicate via a PG Monitor or Autofloat controller with WinPrompt software. Remember to disconnect the power adapter and change the switch to RS485. Details for operation with the PG Monitor or Autofloat controller with WinPrompt are in the WinPrompt manual.

When a LEM is connected directly to a 2456 PG Monitor or 2465 Autofloat Controller the 9-pin serial communications cable is the only cable. It does not need its power adapter cable connected because it will be powered by the PG Monitor or Autofloat controller. Turn the power off to the PG Monitor or Autofloat controller whenever making a change to a cable or switch setting. If you forget make sure to turn them off for a few seconds afterward to reset the logic and search for the LEM.

To use a LEM with COMPASS for Pressure, or other software, see this Article, 2456 LEM Setup in COMPASS for Pressure

If you need more assistance or have questions please contact Pressure Technical Support at the link below or call us at +1.877.355.3225

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