More than two FP-TB-3 with FP-TC-120 
Author Message
 More than two FP-TB-3 with FP-TC-120

I want to use 4 FP-TB-3 with FP-TC-120 and one FP-1000. Then I somehow
need to wire power between the FP-TC-120 modules. The FP-TB-3 has only
one power terminal "C" in each end of module, unlike the FP-TB-1 which
has two terminals "C" and "V". What should I do?


Sun, 13 Feb 2005 03:36:48 GMT  
 More than two FP-TB-3 with FP-TC-120
Hi RMY,
Is there a reason you are trying to power the TC-120 module? Because
these are just taking thermocouple inputs and do not need to be
supplied additional power apart from what they are drawing from the
terminal bases. Their terminal bases either FP-TB-3 or FP-TB-1
automatically draw 350mW from the network module so there is no
express need to connect the V and C terminals for the TC-120 modules.
Plus you are defeating the module-to-module isolation by jumping wires
between the TC-120 modules.

In short you do not need to wire power into the TC-120. The TB-3
terminal base is used by other output modules which need external
power and so have the V and C terminals but the TB-3 is solely used
with the TC module due to the additional cold junction compensation
and so does not need the external power connection.

Hope this helps,
Pravin



Sun, 13 Feb 2005 06:14:53 GMT  
 More than two FP-TB-3 with FP-TC-120
I get 900 mW out of the FP-1000. The FP-TC-120 takes 350 mW each. As
mentioned, I need 4 FP-TC-120. When I mount the FP-1000 to 4 FP-TC-120
+ FP-TB-3 straight ahead, I get error inications on the last two one.
So again, what should I do? Do I have to use FP-TB-1?


Sun, 13 Feb 2005 14:20:57 GMT  
 More than two FP-TB-3 with FP-TC-120
RMY,
The 900mW (approx 1W)is the power consumption of the 1000 module. The
amount of power available to the I/O modules from the network module
depends on the power supply connected to the network module.
The power requirements for a FP bank that uses an FP-1000 network
module are calculated as follows:

Power= 1 watt + 1.55*Summation(I/O Module Consumption )

This is the amount of power the network module consumes from the power
supply to power itself and the I/O modules. It does not include any
power consumed by devices that you wire to the terminal bases.

So in your case, for 4 TC-120 modules you'd need 350*4 = 1.4Watts.
Using the above formula if your power supply can provide 3.17 Watts (1
Watt + 1.55*1.4)you should be good to use either terminal base.

So things to be considered here would be:
1. To find the rating of your external power supply.
2. What kind of error indications do you see?
3. If you swap the last two modules with the first 2 do you see the
same error indications? and in which modules?

Note: In my last post i meant TB-1 can be used by other modules unlike
TB-3.

Pravin



Mon, 14 Feb 2005 00:12:31 GMT  
 More than two FP-TB-3 with FP-TC-120
Sorry Pravin, there was no error after all. I (and the NI phone
support!) supposed something was wrong when some of the channel leds
where on and some of them where off. The reason was bad configuration
(solved with FP Explorer). Some channels where defined as volt inputs,
not thermocouple.

RMY



Tue, 15 Feb 2005 03:02:04 GMT  
 
 [ 5 post ] 

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