Read And Write Protocol - Ametek 2850 User Manual

Read & Write Protocol
For a single controller, the serial address (RS485_Address) is 200; for networked control-
lers, addresses from 201 to 232 are used. When multiple analyzers are networked, the
address of a specific analyzer must precede the first of a string of read/write commands
destined for that analyzer. Press and hold the [ALT] key while entering the 3 digit serial
address. If there is doubt about which of the networked controllers is on line at a given
time, type WHO and the active controller will respond with its serial address.
Read commands consist of the letter R (upper or lower case) followed by the two charac-
ter alpha-numeric ID code for the system value. Refer to Table II for Read Only variables
and ID Codes. For example, to read the current value of cell frequency (Cell_Freq) from
analyzer 201, the command would be [ALT]+201 followed by R12.
Write commands consist of the letter W (upper or lower case) followed by the two char-
acter alpha-numeric ID code for the variable and the data to be written to the EPROM.
The data field has floating decimal format and must not exceed eight characters; plus
and minus signs and trailing zeros are permitted but not required. Valid data values
range from -0.00001 to +999999. Refer to Table III (Chapter 7) for Read and Write vari-
ables and ID Codes. For example, to write a new value of 2.5 to Max_Span on analyzer
201, the command would be [ALT]+201W382.5.
Calibration and zero cycles can be initiated through the serial interface by identifying the
analyzer to be addressed and typing either CAL or ZRO. For example, to start a cali-
bration cycle on analyzer 201, type [ALT] +201CAL. Note that external valves used to
switch the sample or reference gas through the dryer must be switched manually before
using the ZRO command.
6-2
Baud Rate 4 Wire
9600 0
4800 1
2400 2
1200 3
600 4
300 5
2 Wire
10
11
12
13
14
15
2850 Moisture Analyzer