How can I verify communications to my HI 3000 or 4000 series controller?

Sometimes we lose our communications between our Hardy weight controller and our PLC, and we need to know how we can monitor our communcations so that we are notified if that communications is lost. What does Hardy suggest?

The first and primary method to see if you have lost communications with a device would be to monitor the connections in the PLC.  Depending on the device connection and the PLC being used there may be different ways to do this.

However, on the HI 3010, HI 3030, HI 3300, HI 3600, HI 4050 or HI 4060 there are multiple communication protocol options and we know of three different ways to verify you still have communications between the above listed Hardy units and your PLC. These are mapping equations you would enter into the unit. The addresses you need to use would depend on the availability of the data locations in your system. We will use the word 0 or 1 locations for everything in our examples.

NOTE:  Bits used in the example are arbitrary selections for the examples only.
Method #1. Map EO0.0 = ~EO0.0 This says the output bit EO0.0 is not equal to itself. This will cause the bit EO0.0 to change states at the update rate of the unit, which is 55 times/sec for the 3000 series units and 110 times/sec for the 4000 series. If you monitored this bit in the PLC, you should see it changing states and if it ever stops, then you have probably lost communications.

Method #2. Map EO0.0 = EI0.0 This says that the output bit EO0.0 is equal to the input bit EI0.0. So in the PLC, if you change the state of your output bit (which is coming in as our input bit EI0.0), the Hardy output bit EO0.0 would change states. You can then changes states any time you wanted and see the response back. If you did not get the response back, then you probably lost communications. This can also be mapped as a word like: ESO0 = ESI0, which would let you enter in a value other than 0 or 1, and every time you changed the value to your Hardy unit, it should return that value.

Method #3. Map DO0.0 = DO0.1 + ~DO0.1, and ESO0 = ESO0 + DO0.0. This is a little more complicated, but you may like the results better. What this does is in the first mapping, DO0.0 = DO0.1 + ~DO0.1, it makes the value in DO0.0 equal to 1. This is then used to increment the next value. Then in the second equation, ESO0 = ESO0 + DO0.0, we use the output register and increment it by 1 every scan. So now you have a value that is incrementing up constantly. When it reaches the upper bit, it will then go to a neg value and count up from there, so it is constantly changing. This is similar to the first method, but instead of toggling between 0 and 1, this will count up constantly. The value from this will count from -32,768 to +32767 and constantly repeat itself. Now you have a value that if you monitor it and it does not change, then you probably lost communications.