Rockwell Automation SD3000 Drive Configuration, Programming User Manual

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3.6.2 UDC Module Meter Port Setup Registers (Registers 10014017)

Registers 1001-l 017 are used to configure the UDC module’s meter ports. This configuration

determines what variables from the UDC module’s dual port memory are to be displayed on the

meter ports at the end of the UDC scan. At system power-up, the output values of the ports are reset

to zero.

To map a UDC variable to a specific meter port at power-up, refer to table 3.7 and use the following

procedure. Note that the setup register configurations are retained during a Stop All.

Table 3.7 - UDC Module Meter Port Setup Registers

UDC Module Meter Port Setup Registers

Variable Register Number Register

Bit Number Register

Maximum Value Register

Minimum Value Register

Change Setup Register

Meter

Port 1

Port 2

1002

1006

1003

1007

1004

1008

1005

1009

Meter

Port 3

Port 4

1010

1014

1011

1015

1012

1016

1013

1017

1001

For each meter port:

Step 1.

Place the register number of the variable you wish to display in the appropriate Variable
Register Number register.

Step 2.

If an individual bit of the register is to be displayed, enter it in the Bit Number register as 100
(bit 00) to 115 (bit 15).

If the entire register is to be displayed, enter a value of zero in the Bit Number register.

Step 3.

Place the value (maximum 32767) that will represent + 1 OV in the Maximum Value register.

Step 4.

Place the value (minimum 32767) that will represent -1 OV in the Minimum Value register.

Step 5.

Set register 1001 (Initiate Change in Setup) equal to a non-zero value to store the new
setup register configurations in memory.

The UDC module’s meter ports are updated once per scan once the UDC task is running and CCLK

is on. They are updated every 5 milliseconds when CCLK is off.

UDC meter ports can also be set up on-line using the “Setup UDC” selection from the Monitor menu
as described in the AutoMax Programming Executive instruction manual. This setup is valid only until

there is a power cycle, in which case the meter ports default to outputting zero voltage and the UDC

Setup screen is cleared on power-up.

Refer to the UDC Module instruction manual (S-3007) for more information about the UDC module’s
meter ports.

3.6.2.1 Resolution of Meter Port Data

For meter ports, the output values will be clamped at the outside (+ 1 0V) limits. Note that if you
select to display a data range that is narrower than the actual range of the data, your output values

will not change until the value returns to within the range you selected to display. In other words, data

is being updated at the rate described above, but the actual output voltage may not change.

If the actual data being sent to the meter port is significantly smaller than the upper and lower limits
assigned by the programmer, the effective resolution of the 8-bit D/A circuit (1 part in 255) will
degrade. To calculate the step change indicated on the meter port, calculate the sum of the absolute

values of the upper and lower limits (the entire range of possible values) assigned to the port. Then

scale this number by 255 in order to determine the minimum step change that will cause the D/A
output to change. For example, suppose the programmer sets the + 1 0V and 1 OV limits at +4095
and -4095, respectively, but the actual value varies only between +1 024 and -1024. Then:

8190/255 = 32 counts

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