ProSoft Technology MVI56E-GSC/ GSCXT - Manual (Page 91)

MVI56E-GSC ♦ CompactLogix or MicroLogix Platform Reference
Enhanced Generic ASCII Serial Communication Module User Manual
ProSoft Technology, Inc. Page 91 of 140
May 9, 2014
Port 2
Byte Offset Description
251 to 252 Number of characters (0 to 200) in Port 2 receive block (255 to 454). If the receive
data in the module is larger than 200 bytes, multiple blocks will be transferred. Any
block with a value of -1 in this field represents the first or continuation block and the
block contains 200 bytes of data. The last block of data will contain a positive
number in this field that represents the number of characters in the last block.
253 to 254 Number of characters transmitted (0 to 200) from last block write Port 2
255 to 454 Port 2 data received
455 Reserved
Port 2 Status
Byte Offset Description
456 to 457 Port 2 receive state:
-1 = Listening for data
1 = Receiving Port Data
2 = Waiting for Backplane transfer
458 to 459 Port 2 receive character count
460 to 461 Port 2 receive block count
462 to 463 Port 2 transmit state:
0 = Waiting for Data to Send
1 = RTS On
2 = RTS Timeout
3 = Sending data
4 = Waiting for RTS Off
5 = RTS turned off
30 = Intercharacter Delay
31 = Intercharacter Delay
32 = Intercharacter Delay
100 = Message Delay before Transmit
101 = Message Delay before Transmit
464 to 465 Port 2 transmit character count
466 to 467 Port 2 transmit block count
468 to 469 Port 2 error word
470 to 498 Reserved
499 Block Sequence Number (Bumped each scan by module)
The Block Sequence Number (byte 499) is an index value used to signal to the
ControlLogix processor that a new block is ready for ladder logic processing. The
ladder logic must recognize a change in this value and process the data
encapsulated in the input image.
The read block contains the data received on each port and status data for each
port. The two word-length values at bytes 1 & 2 (Port 1 Receive Length) and 251
& 252 (Port 2 Receive Length) define the number of bytes in this input image to
be processed by the ladder logic for each port. Received data for the ports are
found starting at byte 5 for Port 1and 255 for Port 2.