RS485 Serial HELP for Low-level Read Queries

[shawning123]

Hi,

I am trying to communication with some lab equipement (Ebara Turbopump) over rs485. Now I have a Blastronix 2 port RS485 PCI board connect with cabiling to the equipement. But when I try and use NI-VISA to communication, the read times out, which is not particularly useful information because I don't know what part of my query is wrong then.

Below, I've posted some images from their communication protocol, but I am very confused as to how to translate this into a Labview VI. So far I've tried using a String Constant with the example 8.1 (last image, with my slave ID: 001) but I get nothing. I've tried it in both ASCII and Hex with a carriage return at the end.

Any help is very appreciated!!

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[Dennis_Knutson]

Did you right click on your string control and select hex display? You do not send a carriage return at the end. The command is terminated by the the two ETX characters. You could also create a U8 array (set for hex display) and use the Byte Array to String function. If either of those do not work, check your cable and verify it is correct.

[shawning123]

Okay, I tried creating to create the string using an u8 array, but still nothing. However, I am still very new to labview and not exactly sure how to create a proper array of u8/hex. I just created different u8 constant numbers and then fed them into the build array function and then to conversion from Byte to String and then to the Write of the Serial connection.

But how would I go about validating the cable?

[Dennis_Knutson]

You need to take a couple of the free tutorials if you do not know how to create an array constant on either the front panel or block diagram.

The manual should explain how to wire up your serial port. An ohmmeter should be used to check it.