MKS 651C - How to Set a Process Limit Relay; How to View and Adjust a Process Limit Relay; How to Disable a Process Limit Relay

How To Set a Process Limit Relay Cha
p
ter Six: Remote O
p
eration
88
How To Set a Process Limit Relay
There are two process limit relays (also known as trip point relays) in the 651 controller. Each
relay has two trip limits: a high trip limit, and a low trip limit. Refer to Table 10, page 34 for
pinout of the I/O connector to determine which pins are for relay 1, and which are for relay 2.
Use the appropriate pins to configure the relays for normally-open or normally-closed operation.
While the pressure remains within the specified limits, the relay is actuated (a normally-open
contact closes, and a normally-closed contact opens). Whenever the pressure crosses
above
the
high
process limit, or
below
the
low
process limit, the corresponding relay becomes de-actuated
(a normally-open contact opens, and a normally-closed contact closes).
How To View and Adjust a Process Limit Relay
1. To check a process limit threshold, issue the command:
R
xx
ENTER
where
xx
= 10 for the low threshold for process limit 1
11 for the high threshold for process limit 1
13 for the low threshold for process limit 2
14 for the high threshold for process limit 2
The 651 controller responds with the message:
P
x value
where
x
= 1 for the low threshold for process limit 1
2 for the high threshold for process limit 1
3 for the low threshold for process limit 2
4 for the low threshold for process limit 2
value
= pressure limit
2. To change a process limit threshold, issue the command:
P
x value
ENTER
where
x
= 1 for the low threshold for process limit 1
2 for the high threshold for process limit 1
3 for the low threshold for process limit 2
4 for the high threshold for process limit 2
value
= pressure limit
How To Disable a Process Limit Relay
To disable a high limit process limit, set the step 2
value
to full scale.
To disable a low limit process limit, set the step 2
value
to negative full scale.