DTL-DB10-6 View Datasheet(PDF) - Murata Manufacturing

Part Name

Description

Manufacturer

DTL-DB10-6

Interface Board for Serial-Input Electronic Loads

Murata Manufacturing 

DTL-IFB-485

Interface Board for Serial-Input Electronic Loads

Command Syntax (Con'td)

When operating from terminal emulation software, you can

type in BACKSPACE to edit out any unwanted or erroneous

characters before pressing ENTER.

First select the desired range on the A/D channel dipswitch as

shown below:

There is a typically a delay of a few tens of milliseconds after

issuing a command and receiving the response. When

operating from a program, allowance should be made for the

fact that responses are not instantaneous.

Typical Program Sequences

In typical burn in or test set up configurations, there will be

multiple loads and units under test connected to the RS-485

cable. The C (clear) command provides a way of setting every

load to zero either initially or for shutdown or an emergency.

In some systems, it will be desirable to set all the loads to the

same value. The G_xxxx command is the easiest way to do

this. If different load settings are required for each U.U.T. then

either the Axxx_yyyyL or Axxx_yyyy commands will do the job.

Sending an Axxx_yyyyL command will immediately set the

addressed load to the data value yyyy on execution of the

command. Omitting the L (load) character at the end of the

command and just sending Axxx_yyyy has the effect of pre-

loading the data yyyy in the addressed load but not changing

the output current value from its existing state. Sending the L

(load) command will then subsequently update the load.

Typically you can pre-load all the loads with desired data and

with a single L command update all the units together.

The Axxx_?S command will return the status of a load. If it is

operating normally, it will return OK but if the voltage applied

to the load is below its compliance limit (typically 0.6V - 2.5V

depending on DTLXA Series load type) then FAULT will be

returned. This is a simple way to determine if the U.U.T. has

failed. Connecting the A/D channel up to the load output

allows direct reading of the voltage to better than 0.1%

precision using the Axxx_?V command. This way the Unit

Under Test (U.U.T.) output voltages can be monitored

precisely and if desired, controlling software can be

configured to perform data acquisition functions.

Simply sending an address e.g. Axxx followed by a carriage

return will return an OK response from a unit set to that

address. If the address is not present on the system, no

response will be received. This provides a way of initially

checking the system by polling for active units. Similarly the

Axxx_?R (range) command returns data on the range setting

of the A/D channel and its calibration status.

Setting and calibrating the A/D Channel

As supplied, the DTL-IFB-485 will have been calibrated and

will not normally require recalibration for 3 months - 1 year.

The DTL-IFB-485 board does not include any adjustment

potentiometers, instead calibration constants for each range

are stored in non-volatile EEPROM in the microcontroller.

Updating these constants can be performed using the

Axxx_CAL command which is most easily performed using a

PC with terminal emulation software or a dumb terminal.

Note that if any any other combination of switch settings is

selected, you will receive a BAD RANGE response after the

Axxx_CAL or Axxx_?R commands. Connect a voltage

calibrator to the A/D channel inputs (note if these happen to

be connected to the load output, the load is automatically set

to zero during this procedure and will not load the calibrator).

The calibrator should be capable of 0 - 20v output in millivolt

steps. Type in the Axxx_CAL command. You should receive a

response:

Input +0.010V and press ENTER or ESC to exit

The input voltage requested will vary with the range (4.096V

range shown). Pressing ESC will abandon calibration and you

will receive an ERROR response. Also when you run the

Axxx_?R command afterwards, you will receive a response

4.096 UNC - the UNC denoting that this range is no longer

calibrated. If the range is uncalibrated, the raw A/D data is

returned and because of zero offset and gain errors, is likely

to be only 1% accurate.

Pressing the ENTER key will load the zero offset constant into

EEPROM and proceed to the next step unless you have

applied the wrong voltage. A check is made that the input

voltage is within ±100% of the requested value, if not a BAD

INPUT response is returned and calibration is abandoned.

Assuming all is correct you will receive the next response:

Input +4.000V and press ENTER or ESC to exit

If the calibrator input is more than ±2.5% away from the

requested value, you will receive the BAD INPUT message

and calibration will be abandoned. Otherwise, you should

receive the OK response and this range will then be

calibrated. This can be checked with the Axxx_?R command

which should respond 4.096 CAL (in this case). Using the

Axxx_?V command and different calibrator settings, you can

check other input voltages to your satisfaction. Note that

calibration must be repeated on each range to calibrate all

ranges, although this is unnecessary if you operate the DTL-

IFB-485 on one fixed range.

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