Rockwell Automation 1771-TCM,D17716.5.108 TEMPERATURE CONTROL MOD - Manual (Page 51)

Chapter
7
7-1
Monitoring Status Data
This chapter shows you how to monitor status data from the 1771-TCM
module. This includes.
sequence of block-transfers
block identification
inferred decimal point
the system status block
At initial start-up, you must write (block-transfer) the dynamic block to the
1771-TCM module to establish its mode of operation. After that, you must
send a dynamic block to the module any time you want to change its
operating mode.
Thru the dynamic block, you also control the module’s response to the
execution of a block-transfer read instruction. The module can send either
a gains block or a system status block in response to a a block-transfer read
execution. Whenever you want the module to switch from sending the
system status block to sending the gains block or switch from sending the
gains block to sending the system status block, you must send a dynamic
block to establish that mode of response to block-transfer reads.
The first word of each system status block contains a block identification
code (1000 1000 1111 1111 or 88FF
16
) that you use to determine that the
module has sent a system status block in response to a block-transfer read.
For the CV value, PID error value, and temperature values, you read a
16-bit signed integer value. However, as you read the value you must be
aware of an implied decimal point.
For the CV value, the implied decimal point is 2 places from the right
(causing the resolution to be 0.01%).
For the PID error values and the temperature values (words 27 thru 34
and 43 thru 59), the implied decimal point is 1 place from the right
(causing the resolution to be 0.1).
Chapter Objectives
Sequence of BlockĆtransfers
Block Identification
Implied Decimal Point