ART Manual Blocker

Owned by Tony LeBlanc
Last updated: Jan 28, 2021
4 min read

The ART manual blocker communicates with Rx-Universe using standard VC DCS protocol, but has some specific behaviour to ensure data is correctly received and sent.

First, the ART-M makes a request of the LMS for each eye separately, and uploads data for each eye separately; however, it receives data for both eyes with each request, and uploads data for both eyes, mirroring the data received for the eye not blocked.  It also needs to receive all prism information for both the blocker and the generator, so that the ART-M can "decide" how much prism will actually be blocked, and therefore how much must be generated.

The sequence of requests and uploads is:

  1. ART-M request data for a job.
  2. LMS responds with data for both eyes
  3. ART-M will upload SVAL, AVAL, KPRVA, KPRVM, PIND, GRPVA, GPRVM, _BLKDM, _BLKRD and _BLKCEHI.  The data for the RIGHT eye is what was actually blocked; the data for the left eye is a mirror of what was received from the LMS.
  4. ART-M will request data for the same job a second time; this is used for the left eye blocking.  Therefore, the data uploaded for the right eye must be re-sent to the blocker, but the left eye data should be that as calculated by the LMS
  5. ART-M will upload SVAL, AVAL, KPRVA, KPRVM, PIND, GPRVA, GPRVM, _BLKDM, _BLKRD, and _BLKCEHI with data for the LEFT eye; the right eye data is also present, and is a mirror of what was received from the LMS in step 4.

In Rx-Universe, the device session for the ART-M should be set up with 2.00 degrees of prism to be sent to the generator (with the remainder blocked), and a maximum blocker prism of 4.00.  (Note that the generator prism is a guideline; the ART-M will calculate the actual amount of prism to be both blocked and generated).  The checkbox indicating the device is an ART blocker must also be checked.

An example will help illustrate the sequence of downloads and uploads of the data.  Take job 12345, which is a 2-eye job, requiring 3.50 degrees of prism on the right eye, and 2.50 degrees of prism on the left eye.  With the ART blocker configured as above (details of the communication sessions are abbreviated for clarity):

  1. ART-M requests data for the job, and Rx-Universe responds with data including (but not limited to):
    JOB=12345
    DO=B
    GPRVM=2.00;2.00
    GRPVA=90;90
    KPRVM=1.50;0.50
    KPRVA=90;90
    PIND=0;0
    SVAL=7.2;7.2
    AVAL=13.0;13.0
  2. The ART-M blocks the right lens, and uploads data as follows:
    JOB=12345
    GPRVM=1.75;2.00
    GPRVA=90;90
    KPRVM=1.75;0.50
    KPRVA=90;90
    PIND=0;0
    SVAL=6.9;7.2
    AVAL=13.0;13.0
    Note that some right eye data has been modified from what Rx-Universe originally sent; GPRVM is sent back as 1.75 for the right eye, but the left eye data remains 2.00, as received from Rx-Universe.  Because the ART-M changed the value for GPRVM, it also changes the value for KPRVM (so that the total prism remains the same).  Rx-Universe then saves the value for GPRVM (and other labels) for the right eye.
  3. The ART-M requests the same job again.  Rx-Universe responds with the same labels as the first time the job was requested, but this time the values are different - the values for the right eye for any labels which were uploaded will be the uploaded values:
    JOB=12345
    DO=B
    GPRVM=1.75;2.00
    GRPVA=90;90
    KPRVM=1.75;0.50
    KPRVA=90;90
    PIND=0;0
    SVAL=6.9;7.2
    AVAL=13.0;13.0
    Note that the values for GPRVM, KPRVM, and SVAL are the values the ART-M returned during the previous communication session.
  4. The ART-M will block the left lens, and upload the new data; that for the left eye is calculated, data for the right eye is a mirror of what was received:
    JOB=12345
    GPRVM=1.75;1.75
    GPRVA=90;90
    KPRVM=1.75;0.75
    KPRVA=90;90
    PIND=0;0
    SVAL=6.9;6.8
    AVAL=13.0;13.0

If the total amount of prism required for a job exceeds that allowed in the generator prism field + maximum blocker prism field (assuming both are >0), then an error is raised when the job is requested by the ART-M (rather than the error being raised when the job is requested by a generator as with other devices).

Settings on the blocker itself

The ART blocker has two connections to Rx-Universe - one to request job information, in which case it acts as a SBK device, and a second session to upload data - this second session needs to be an UPL session.

Settings for the generator interface

If you are running Rx-Universe version 7.35.00 or earlier, and using an ART-M, the blocker does not upload BLKD and RNGH information.  If the lab uses ONLY ART blocking, you will need to configure the generator interface to set these values.  Do this, on the generator configuration, VCA Over-rides tab, as follows:

Note this is NOT necessary for Rx-Universe version 7.36.00 and later.