1762-IR4 RTD Module - Cyclic Calibration
Sorry for the delay. I hadn't time to look into this for you until today...
Jason Ozolins said:
...Is it possible in a 1400 to access/write to the configuration word 4, bit 0 via ladder?...I'd like to disable/enable the autoconfig in the program.
I think the screenshots that you've posted up are from
Publication 1762-UM003A-EN-P (1762-IR4) and the word arrangement is from Page 3-7, while the "TIP" is from Page 3-20.
They seem to suggest that this 1762 RTD module will allow you to write to the Configuration words through ladder logic, but as far as I can tell, this does not seem to be the case, normally. I have never attempted to do this before having always just configured the module as normal.
The 1762-IR4 RTD module can be used with the MicroLogix 1100, 1200 and 1400 controllers. When you add this module to the
IO Configuration for these controllers, it automatically creates the six Input words addressed to the slot it was added to. Four Input words (Word 0 - 3) are used for the module's four individual Inputs and two Input words (Word 4 & 5) are used for the Status data - General Error, Open Circuit, Over-Range or Under-Range. These Input words are exposed to the user so they can read the Input and Status data from the module and use those addresses in ladder logic.
The module also uses five Configuration words. Four of these words (Word 0 - 3) are for the configuration of the module's four individual Inputs and one word (Word 4) is used just to Enable/Disable the
Cyclic Calibration mode. However, while the six Input word addresses are exposed to the user, the five Configuration word addresses are not. These Configuration words are only made available to the user via the module's
Adv Config tabular user interface. When you make changes under these tabs they are writing to the Configuration words in the background. On the
cal tab you can Enable/Disable the
Cyclic Calibration mode. There are no Output addresses created for this module and so a user cannot address the configuration words from ladder logic.
I/O addressing after adding a
1762-IR4 - 4 Channel RTD/Resistance Module to slot 1...
I have added this module to a MicroLogix 1100, 1200 and 1400 controller and they all do not create Output addresses for this module. With no Output addressing, there is no way for a user to write to Configuration Word 4, Bit 0 from ladder logic. You can only Enable/Disable
Cyclic Calibration via the
Cal tab...
While they say in the above
TIP from Page 3-20 that you can change this bit using ladder logic in controllers that support it, they also give this counter
TIP on Page 3-2...
What I fail to see is which controllers, be they Allen Bradley or "other", are they referring to as supporting this feature? To my knowledge, the 1762 modules are only used with the above mentioned MicroLogix 1100, 1200 and 1400 controllers; all of which do not allow user access to this bit via ladder logic, normally. (There is that word again...)
Digging deeper...
If you look at the
Expansion General Configuration tab for the module you will notice the
Input Words and
Output Words fields. These values define the number of I/O word addresses that will be created for the module. The
Output Words field is
0 and Grayed out. So we cannot manually add
Output Words for this module, which is what you would need. It is Grayed out because we have added a predefined module from the list of 1762 modules which automatically assigns the I/O addressing. It does not assign the necessary five Configuration words in the
Output Words field, but instead, and because it uses a user interface, it uses five words in the
Extra Data Length field beneath...
This allocates, in the background, the necessary five words in the controller's memory for the configuration data manipulated on the user interface tabs.
I have said "normally" a couple of times so far. Here is what I think might abnormally be the case...
What I think they might be referring to is the original option for these modules when they were released to manually add and define them as a generic module. At their release, the then current RSLogix 500 version (v5.20) did not have these modules available for selection under the
IO Configuration. They were not available for selection until RSLogix v5.50. So, for RSLogix v5.20 or earlier, you would have to add these modules using the
Other -- Requires I/O Card Type ID option at the bottom of the list.
When you add a generic module you need to manually define the Vendor specific information and I/O size, etc. For this module you can add a generic module instead of the predefined module and then enter the same Vendor specifics and I/O size as the predefined module. This will give you the same results as when adding the predefined module from the list. Next you can delete that and add a generic module again, only this time also enter
5 in the
Output Words field. Now you will have the same as the predefined module except now the five Configuration Output words will also have been created...
Now you have Output addresses to use in the ladder logic. The relevant bit address being for Cyclic Calibration being O:1.4/0. You should not modify any of the other Word 4 bits or indeed the value of Word 4 itself. Whether these addresses will actually work from the logic and configure the module, or not, I do not know. I do not have an RTD module to hand to test, but it is something you could try, if you wish.
But, there is a problem with the user interface. When I add this module as a generic module, and also add the five
Output Words, it does not play well with access to the user interface tabs. I am getting a message when I attempt to open any of the other tabs...
Best guess is that it is referring to the
Output Words field and how it is expecting it to be
0 in value. This message suggests to me that my attempt at exposing the five Configuration words is messing with the module's expected I/O size. This could be because my version of RSLogix 500 does have the module in its list and when you configure the Vendor specifics the software auto recognizes the module's predefined configuration and then there is a mismatch of sorts. I would like to try adding this module generically in RSLogix 500 v5.20 or earlier, where the predefined module configuration is not present, but I do not have a version that old installed on anything anymore.
While not being able to access the Configuration tabs is a stumbling block, it might not be a job stopper. If the newly created five Configuration Output words do work, then you could do all your configuring via these words and ignore the tabs. But some of the settings are finicky under the tabs and may be difficult to figure out when you need to enter equivalent values in the relevant Output words. However, there is also a way around this.
When you add this module proper, and you have access to the tabs, you can go to the
Generic Extra Data Config tab. Here you will see five values to the right that represent the five Configuration Word values (Word 0 - 4, left to right)...
With the default configuration i.e. a freshly added module, all values should be equal to
0. If you then configure the settings you require, such as enabling a Channel, and go back to that tab, you will now see a value changed. For instance, if you just enable Channel 0, then from the manual you can see that Word 0 Bit 15 is set. This is reflected on the
Generic Extra Data Config tab as the left most value equal to
-32768...
As we know, for a 16-bit Signed Integer, having just Bit 15 set will equal -32768. If you then say enable all four Channels and disable the
Cyclic Calibration mode, you will now see all four Channel Word values equal to
-32768 and Word 4 equal to
1...
Then let's say for each Channel we change the
Data Format to
Engineering Units, set the
Units to
°F and enable
Cyclic Calibration...
So you can see how the values reflect the current configuration.
More to come...